All devices dropping connection intermittently to RT-AC66U after upgrading Modem

[Christopher Phillips]

I just recently upgraded my Comcast cable internet to gigabit and as such had to get a new cable modem that supports DOCSIS 3.1. I ultimately went with the Motorola MB8600 (although now I'm regretting not sticking with an Arris modem since my last one was so solid.)

Ever since making the upgrade, all devices on my network will drop their connect wtih my Asus RT-AC66U router 3-4 times a day. It's not that they just lose internet, they drop connection with the router all together. This occurs on both my wireless and wired devices. On MacOS, Windows, and Android. They drop connection for about 15-30 seconds and then will automatically reconnect.

I thought maybe my router was going bad so I switched back to my old Docsis 3.0 Arris modem to confirm and the problem went away. I would just return this Motorola to get the Arris DOCIS 3.1 modem but I missed the return window and Amazon won't let me return it.

My ASUS RT-AC66U is running the last version of MerlinWRT (380.70) before they stopped supporting my model of router.

This router combined with MerlinWRT has been so solid. I want to say the issue with the modem but it's odd to me that if the modem was the problem that my devices would be dropping connection to the router specifically.

It may be time to just upgrade my router since my firmware is so old but I don't want to if the problem is the modem.

I've attached a log of my router. The last time this happened was June 15th around 11am. Looking at the logs my router does this weird thing right when my connection gets dropped where it forgets what day it is and jumps back to July 31 which I thought was the culprit but even when I switched back to my old modem it did that but without dropping internet (I think).

Any thoughts/advice would be much appreciated. Maybe I should just buy a new router but I'd like to get people's thoughts on what's going on. Thanks in advance!

 

[dave14305]

I just recently upgraded my Comcast cable internet to gigabit and as such had to get a new cable modem that supports DOCSIS 3.1. I ultimately went with the Motorola MB8600 (although now I'm regretting not sticking with an Arris modem since my last one was so solid.)

Ever since making the upgrade, all devices on my network will drop their connect wtih my Asus RT-AC66U router 3-4 times a day. It's not that they just lose internet, they drop connection with the router all together. This occurs on both my wireless and wired devices. On MacOS, Windows, and Android. They drop connection for about 15-30 seconds and then will automatically reconnect.

I thought maybe my router was going bad so I switched back to my old Docsis 3.0 Arris modem to confirm and the problem went away. I would just return this Motorola to get the Arris DOCIS 3.1 modem but I missed the return window and Amazon won't let me return it.

My ASUS RT-AC66U is running the last version of MerlinWRT (380.70) before they stopped supporting my model of router.

This router combined with MerlinWRT has been so solid. I want to say the issue with the modem but it's odd to me that if the modem was the problem that my devices would be dropping connection to the router specifically.

It may be time to just upgrade my router since my firmware is so old but I don't want to if the problem is the modem.

I've attached a log of my router. The last time this happened was June 15th around 11am. Looking at the logs my router does this weird thing right when my connection gets dropped where it forgets what day it is and jumps back to July 31 which I thought was the culprit but even when I switched back to my old modem it did that but without dropping internet (I think).

Any thoughts/advice would be much appreciated. Maybe I should just buy a new router but I'd like to get people's thoughts on what's going on. Thanks in advance!

Your router is rebooting when this happens, according to your log. Could be a power or heat issue if you’re trying to push gigabit through this older router.

I’m not so savvy on the hardware side, but you might benefit from upgrading to John’s fork for current firmware.

But in the end you probably want a newer faster router to match your new gigabit speed.

 

[SoCalReviews]

Any thoughts/advice would be much appreciated. Maybe I should just buy a new router but I'd like to get people's thoughts on what's going on. Thanks in advance!

Make sure you are using Cat6 or Cat7 interconnect Ethernet cable between your modem and the Asus router. If that doesn't work then YES you will want to consider upgrading your Asus router to a newer model with a dual core or more processor. As mentioned by a the previous poster your RT-AC66U is an older single core design and may not be able to handle Gigabit Internet throughput loads very well. Also check with your cable Internet provider techs support and make sure there aren't any compatibility issues with your newer modem and your model of Asus router (or newer model you are planning to buy).

If you upgrade to another Asus router I wouldn't buy anything less than the AC68U model in terms of performance. Most newer dual core ac and ax routers should be able to easily handle at least 400-600 Mbit/sec throughput via wired or wireless on your local network but do some research and read some of the reviews about the newer models to make sure that whatever you buy will efficiently handle closer to the Gigabit Internet throughput. If you are using hard wired Ethernet cable to your computers, switches and devices make sure it is also capable of handling the higher data throughput from your router.

 

[ApexRon]

You cannot arbitrarily swap cable modems as each one has a unique MAC address. Comcast needs to know the MAC address of your new modem so that they are assured that no one is pirating your cable service. Only one modem will work with Comcast and if it's your old one then that's the MAC address it is expecting. If funky stuff is happening when you plug in the new modem then it may be because Comcast doesn't like the MAC address.

 

[Grisu]

change power adapter, could be the reason of reboots.

 

[Christopher Phillips]

Thanks everyone for the replies. I've gone through and replied to each of your ideas below.

Your router is rebooting when this happens, according to your log. Could be a power or heat issue if you’re trying to push gigabit through this older router.

I’m not so savvy on the hardware side, but you might benefit from upgrading to John’s fork for current firmware.

But in the end you probably want a newer faster router to match your new gigabit speed.

If it was rebooting I would have thought it would take longer than 15-30 seconds to come back online. Next time it happens I'll walk over to the router to see if it looks like it restarted.

I went ahead and switched to the standard Asus firmware which is a lot more up to date and so far I haven't had any drops and the logs haven't reset back to July 31 but it hasn't been that long so I'll give it some more time. I'll look into John's firmware also.

Good call on the possible heat issues. I hadn't considered that but it's definitely a possibility. I will look to see if there is any temp monitor on my router I can check.

Make sure you are using Cat6 or Cat7 interconnect Ethernet cable between your modem and the Asus router. If that doesn't work then YES you will want to consider upgrading your Asus router to a newer model with a dual core or more processor. As mentioned by a the previous poster your RT-AC66U is an older single core design and may not be able to handle Gigabit Internet throughput loads very well. Also check with your cable Internet provider techs support and make sure there aren't any compatibility issues with your newer modem and your model of Asus router (or newer model you are planning to buy).

If you upgrade to another Asus router I wouldn't buy anything less than the AC68U model in terms of performance. Most newer dual core ac and ax routers should be able to easily handle at least 400-600 Mbit/sec throughput via wired or wireless on your local network but do some research and read some of the reviews about the newer models to make sure that whatever you buy will efficiently handle closer to the Gigabit Internet throughput. If you are using hard wired Ethernet cable to your computers, switches and devices make sure it is also capable of handling the higher data throughput from your router.

That's a good point. the cable I have between my modem and my router is only Cat5e which supports up to 1Gbps but still would be a good idea to get a Cat6 cable.

I've absolutely love my Asus router so I plan on sticking with that brand. I'm perfectly fine paying extra money for a better router. If you have an Asus specifically you can recommend I'd appreciate it. I did some research a few weeks ago and there were a bunch that all seemed to be on the high end so wasn't quite sure which one would be best.

I saw that the modem I got was compatible with Comcast but did not check to see if the modem/router combo was. I honestly didn't even know that modem/router compatibility concerns was a thing.

You cannot arbitrarily swap cable modems as each one has a unique MAC address. Comcast needs to know the MAC address of your new modem so that they are assured that no one is pirating your cable service. Only one modem will work with Comcast and if it's your old one then that's the MAC address it is expecting. If funky stuff is happening when you plug in the new modem then it may be because Comcast doesn't like the MAC address.

Each time I switch back I go through the motions to activate the new modem through Comcast's online tool.

change power adapter, could be the reason of reboots.

If it was the power adapter I wouldn't have thought changing the modem it's connected to would be what's causing the issue. It only seems to happen when the newer modem is plugged in.

 

[dave14305]

If it was rebooting I would have thought it would take longer than 15-30 seconds to come back online. Next time it happens I'll walk over to the router to see if it looks like it restarted.

You can see the uptime on the System Log page.

 

[Grisu]

Do you see disconnect/reconnect of WAN-port in your syslogs?
Few have seen problems on LAN ports with some devices, to test this use a switch between router WAN and modem, if it stops to happen it will tell you there is some ethernet incompatibility with the new modem.
No need for CAT6, 5e is more than good for your need as you wont need full 100m distance, but bad cable/connectors can be an issue.
If you go the way with a new router take the RT-AC86U (new and very strong HW for a reasonable price).

 

[Christopher Phillips]

Do you see disconnect/reconnect of WAN-port in your syslogs?
Few have seen problems on LAN ports with some devices, to test this use a switch between router WAN and modem, if it stops to happen it will tell you there is some ethernet incompatibility with the new modem.
No need for CAT6, 5e is more than good for your need as you wont need full 100m distance, but bad cable/connectors can be an issue.
If you go the way with a new router take the RT-AC86U (new and very strong HW for a reasonable price).

OK cool, I figured Cat5e would be sufficient.

Asus has a bevy of routers on their website and it's incredibly difficult to tell the differences between all of them, even with their comparison tool. I'm trying to see if I can find a product release schedule to see which ones are the newest. The ROG ones seem to be the beefiest but I don't want/need a router with 8 antennas, lol.
However, I just found a press release that introduced a new line of ax routers which will be released in Q3 of 2019 so I'll probably just wait for that since so far, switching to the Asus firmware seems to have solved the problem.

https://www.asus.com/us/News/rU7DdBAsBXMQ5cn0

I appreciate taking the time to help me out!

 

[L&LD]

OK cool, I figured Cat5e would be sufficient.

Asus has a bevy of routers on their website and it's incredibly difficult to tell the differences between all of them, even with their comparison tool. I'm trying to see if I can find a product release schedule to see which ones are the newest. The ROG ones seem to be the beefiest but I don't want/need a router with 8 antennas, lol.
However, I just found a press release that introduced a new line of ax routers which will be released in Q3 of 2019 so I'll probably just wait for that since so far, switching to the Asus firmware seems to have solved the problem.

https://www.asus.com/us/News/rU7DdBAsBXMQ5cn0

I appreciate taking the time to help me out!

I'm not sure where you see anything new being released in a few months this year? All of those are available since last year, afaik. At least, the tech inside is nothing new we can't buy currently.

The 'real' AX (fully hardware supported, including OFDM enabled hardware) routers are expected in about a year from now (earliest is Q1 2020) and should finally offer all the benefits that AX promises (at least the top tier models).

Other than the draft AX routers any manufacturer is selling today, the most current/powerful Asus router you can buy is the RT-AC86U for a 1Gbps up/down ISP connection.

With RMerlin firmware, the RT-AC86U makes for a very potent combination for your network.

When 384.12 goes to release status (currently in a very stable Beta 2 incarnation), you may want to consider moving to it from the stock Asus version you're running now.

I would also recommend following the M&M Config guide to ensure that the firmware has the best chance of working properly in your network with your older router too.

Please see my signature below for the link to the M&M Config guide (or better yet: the Nuclear Reset guide), to move to the new firmware and have your router and network in the best good/known state possible.

 

[Christopher Phillips]

I'm not sure where you see anything new being released in a few months this year? All of those are available since last year, afaik. At least, the tech inside is nothing new we can't buy currently.

The 'real' AX (fully hardware supported, including OFDM enabled hardware) routers are expected in about a year from now (earliest is Q1 2020) and should finally offer all the benefits that AX promises (at least the top tier models).

Other than the draft AX routers any manufacturer is selling today, the most current/powerful Asus router you can buy is the RT-AC86U for a 1Gbps up/down ISP connection.

With RMerlin firmware, the RT-AC86U makes for a very potent combination for your network.

When 384.12 goes to release status (currently in a very stable Beta 2 incarnation), you may want to consider moving to it from the stock Asus version you'righre running now.

I would also recommend following the M&M Config guide to ensure that the firmware has the best chance of working properly in your network with your older router too.

Please see my signature below for the link to the M&M Config guide (or better yet: the Nuclear Reset guide), to move to the new firmware and have your router and network in the best good/known state possible.

Oh shoot, you're absolutely right. I saw June 4th and totally didn't realize that was from 2018.

I have the original RT-AC66U, not the B version so as far as I know, AsusWRT-Merlin stopped supporting it a long time ago. Should I still try the newest firmware on my old router?

I may just pull the trigger then on the RT-AC86U if the AX units are really that far out. What does M&M stand for?

I'll definitely check out your guides. I'm glad I found this forum. Thanks again!

 

[Grisu]

What does M&M stand for?

just read his signature and the link inside

And you could try Johns fork for 66U, he still updates his firmwares.

 

[Christopher Phillips]

Changing over to the stock firmware didn't resolve the issue. The router is definitely restarting as most of y'all suggested. The uptime reset when I lost connectivity.

I'm going to go ahead and buy the RT-AC86U. I got this router in 2013 so 6 years is pretty damn good longevity for tech. Before this router I had tried Dlink, Linksys, Netgear. I was never impressed with any of them. This Asus router was definitely a breath of fresh air, especially combined with RMerlin.

Thanks again everyone for your help. I will be sure to look to L&LD's guides and the rest of this forum for setting up my 86U and getting the most out of it!

 

[SoCalReviews]

No need for CAT6, 5e is more than good for your need as you wont need full 100m distance, but bad cable/connectors can be an issue.
If you go the way with a new router take the RT-AC86U (new and very strong HW for a reasonable price).

I disagree about not needing Cat6 or better for modem to router interconnect cabling. It's not always a matter of need but it's a matter of performance. It is a short run but it's a critical data transfer link. Cat 5e might work and you may not seem to be having problems but if you have a lot of different cabling such as USB 3.0, power cords, etc.. in close proximity to the outside of the Ethernet interconnect cabling then you could be getting intermittent high frequency interference from those other cables. This is especially true when using active USB 3.0 devices or other cheap cabling with your router. Cat6's extra twists and especially Cat7 with it's shielding will be more resistant to this outside interference.

There is a difference between digital data signal "working at all" and having it work optimally. Your connection might seem to be working fine. However, if you are unknowingly getting dropped data packets between the modem and router and the digital packets are being constantly resent you are not getting the maximum bandwidth you are paying for even if you believe it's working ok. Good quality Cat7 10Gb rated internet connect cables are very inexpensive these days... less than $10 USD for one meter. Considering the monthly cost of 1Gb internet service why wouldn't you just eliminate any potential problems and just use premium Cat7 interconnect cable to go with that expensive premium internet service?

Regarding the Asus router... I don't know much about the RT-AC86U model. It seems to have good specs and it might be a great high speed router. I actually use a RT-AC1900P and RT-AC86Us and those routers are rock solid but if I had 1Gb internet service and I was going to buy a newer Asus model I would look at the RT-AC86U or wait for the newer AX/Wifi 6 models.

 

[Grisu]

I disagree ...

Our whole company with >10k employees uses Cat5e with Gb, sure your home needs more
Cat5e runs even 2.5G and 5G@75m
https://en.wikipedia.org/wiki/2.5GBASE-T_and_5GBASE-T
Out of wiki: The IEEE Standard 802.3bz defines: 2.5 Gbit/s up to at least 100 m of Cat5e
And Cat7 is a lot more work to do than 5e or 6!

But sure you will need Cat8 @home because of your electrical plant.

Believe it or not, you will not get one bit faster after changing your cabling, industry for sure is happy you are a believer.
If you see any difference there is only one reason for it: not well done, maybe connectors - but never the cable itself!

 

[SoCalReviews]

Our whole company with >10k employees uses Cat5e with Gb, sure your home needs more
Cat5e runs even 2.5G and 5G@75m
https://en.wikipedia.org/wiki/2.5GBASE-T_and_5GBASE-T
Out of wiki: The IEEE Standard 802.3bz defines: 2.5 Gbit/s up to at least 100 m of Cat5e
And Cat7 is a lot more work to do than 5e or 6!

But sure you will need Cat8 @home because of your electrical plant.

Believe it or not, you will not get one bit faster after changing your cabling, industry for sure is happy you are a believer.
If you see any difference there is only one reason for it: not well done, maybe connectors - but never the cable itself!

I run Cat5e Ethernet from my router to my computers and devices, printers, etc.. as well. I wasn't talking about those runs. I was talking about the modem to router Ethernet cable which is often next to a lot of other cabling like USB 3.0 that has been known to cause high frequency interference for some users. It's been recommended by members of this forum for many years to try changing that cable to a better cable if it's Cat5 or cheap Cat5e. It actually has been a commonly suggested and successful solution for fixing inconsistent speeds and other problems for forum posters in the past.

Hundreds of dollars are spent on expensive routers with questionable features and Gigabit Internet service can cost hundreds of dollars USD per month and it often doesn't effectively achieve Gigabit download speeds in real world downloading from internet sites... but a one time cost of as low as $6 USD for a meter run of higher quality shielded Cat7 interconnect Ethernet cable is less than the cost of a cup of gourmet coffee. Even if you really believe it may not be required... why does the suggestion of upgrading the quality of that modem to router Ethernet cable link need be so meticulously scrutinized and debated?

 

[Grisu]

You dont know how his cables run, he never mentioned there is more than this one, no USB or whatever.
And we dont know if its done with only a short patch cable or he will need recabling his home by professionals which will be really expensive, its not the cost for 1m or some more cable. And especially CAT7 is a lot more work to connect.
I agree it can be a problem, but then he would see the port going down and up all the time.

Rather there are incompatibilities between ethernet chips, often solved with a switch between (easy to test) and problems are gone!

Maybe this here can help too: https://www.snbforums.com/threads/stock-firmware-rt-ac1900-wan-still-drops.57088/#post-498118