New RT-AC88U has a totally unstable connection

[Kettch]

Hello,

I just bought and installed a brand new Asus RT-AC88U, and just did a minimal configuration for starters. Unfortunately, while the Web GUI says that the router is connected properly through my ISP modem, on all of my machines the connection will grind to a halt constantly. I'm not sure if it's disconnecting (but doesn't look like it), or just stopping and going constantly, but nothing will pass through for a few seconds, then it will come back for a few seconds, and so on... I tried doing a continuous ping to google.com, and ended up with a 60% packet drop overall.

So far, here's what I tried:
- changing the Ethernet cable to the modem
- updating to the latest firmware
- trying out the latest Merlin firmware, as well as an oldest one (from around January '18)
- resetting to factory defaults on the latest official firmware

The modem is the one from my ISP, where I disabled the router & DHCP to put it in bridge mode, when plugging in the AC88U. When reverting to the modem's default router, everything is working fine.

I see nothing in particular in the logs, except for restarts of the UPnP service (which I ended up disabling).

So far, I'm quite lost as to how to diagnose or try to fix this. Any ideas would be welcome, and if I'm missing some info on the configuration here, I'd be happy to add more details!

Thanks!

 

[ApexRon]

@Kettch
Don't use your ISP provided device in bridge mode, at least right now, as that can make resolving your problem more challenging.

First thing is to remove the ASUS from the equation completely. If the ISP device has WiFi, disable it. Then using your ISP's device get an Ethernet device of yours (laptop or pc) to work to your satisfaction. Verify that the device confirms the ISP speeds you're paying for.

Once that is completed, disconnect the Ethernet cable from your device and plug the cable into the WAN interface of the ASUS. Now we need to confirm the Ethernet connected speed.

On the ASUS GUI Network Map screen at the lower right hand corner you should see that the WAN connection is 1Gbps and doesn't change. Further, go to the System Log and make sure that you don't see a port changing back and forth between 500Mbps and 1Gbps.

Assuming that there is no issue as yet, plug that same device you were using into an Ethernet LAN port using a different cable. Verify that the device confirms the ISP speeds you're paying for.

ADVISE

Please ensure that the ASUS has either release 12 or 13 installed.

Please advise as to the make and model of ISP provided device.

 

[Kettch]

Thanks for the advice, Ron!

I did as you suggested, and without the Asus I'm getting the usual speeds I'm expecting, with the Wifi disabled.
I then plugged in the Asus, with only the one single device, and everything looked fine again, with speed in the same ranges. The speeds in the Asus interface are not showing as 1 Gbps, since I'm not using cables that would support those, but as 100 Mbps. Still, that should be sufficient for the speeds I'm getting for my DSL line.

After replugging all the other devices on the Asus, everything seems to be working fine again.

So, maybe the cause would be having the modem in bridge mode? But then, the point of having an external router was to have better configuration options on it, so keeping the modem as a router as well will be problematic.
The modem is a Freebox V5 (from the french ISP "Free") on a DSL line.

 

[ApexRon]

The speeds in the Asus interface are not showing as 1 Gbps, since I'm not using cables that would support those, but as 100 Mbps.

And that's your problem. You need to purchase an Ethernet cable, of the appropriate length, that is Category 5 e or higher.

Since I don't speak French I am not going to be able to read and support information for the Freebox V5 but I suspect you can't configure to force a port to 100Mbps, most products on the market today depend on Auto-Negotiation to set speed.

Depending on how the ASUS senses that a 1Gbps connection is not possible, the ASUS may be attempting to Auto-Negotiate the speed continually which could slow down throughput rate by as much as 50%.

Today, ISP are not consistent with regard to having their modem/router placed in bridge mode and with a customer owned router attached.

When I ran the AT&T DSL modem/router in bridge mode with my current ASUS connected, AT&T would go through the DHCP handshake every 30 seconds making my throughput {insert your own swearword}. I ran my router off the AT&T DSL modem/router as a second NAT device with zero issues for many years.

Therefore, I recommend you obtain an Ethernet cable that is 1Gbps capable and use it to connect your ASUS to the Freebox V5, confirming on the ASUS that the WAN connection is 1Gbps. DO NOT place the Freebox V5 in bridge mode and run the ASUS as a second NAT device. Then connect your device to the ASUS Ethernet port and validate the speed. If you are satisfied with the speed then move on the ASUS WiFi speed. After that, then you could try putting the Freebox V5 in bridge mode.

 

[Kettch]

Well that's weird then, because the cables are Cat 5e. I'm using the one that came with the Asus, and also another one that is marked as being 5e, and it still showed as 100 Mbps between the Asus and the modem. So I'll check the documentation for the modem to see if it wouldn't be the one limiting the rate, because maybe it just can't support more (it's an old one, unfortunately).

Still, now everything looks fine, and after an hour, I didn't have the issue that I had yesterday. I'll check that and do the next tests you are suggesting, but it kind of looks like the bridge mode might be the culprit.

Thanks a lot for the help!

 

[Grisu]

Connect your PC/laptop via LAN to the modem to see if it supports 1Gb/s.
I think it got only 100Mb/s ports, as it only has 2,4 802.11g WPA, no WPA2 and no 5G.
https://translate.google.com/transl...reur-hd-fiche-technique-1273.html&prev=search

Here you will find only 5x 100Mb/s: https://translate.google.com/translate?hl=de&sl=fr&tl=en&u=http://socialcompare.com/en/comparison/comparatif-freebox-v7-vs-v6-vs-v5-vs-v4
https://translate.google.com/translate?hl=de&sl=fr&tl=en&u=http://socialcompare.com/en/comparison/comparatif-freebox-v7-vs-v6-vs-v5-vs-v4

 

[Kettch]

Yes indeed, I checked and it's limited to 100 Mbps on all ports, so everything's normal there. Obviously, I'm looking forward to the new modem with optical line and 1Gbps, but for now I'm stuck with this one

Anyhow, I continued with the tests that Ron was suggesting. Started with enabling the Wifi on the Asus, and everything was still fine after a few hours.
So I went ahead and put the modem back in bridge mode, and so far so good, everything looks fine!!

Maybe it was the Wifi still being enabled on the modem (even though putting it in bridge mode is supposed to disable it), or maybe something else and we'll never know.

Many thanks to you, Ron, for helping me through this one!!