Xfinity Gigabit x2 Plan and ASUS RT-AX86U

[phillyaj]

Greetings all,

While I wait to get an Xfinity tech who knows what they are going, I figured I would go ahead and post something here...

Here's the Situation.

- I had Xfinity 1G service for a while. Was getting about 900M - 1G bps average down and 41.4Mbps up...fairly consistently. This while using my own Arris S33 Modem, and the ASUS RT-AX86U (running ASUSWRT-Merlin), connected with 2.5G port on both.
- Got an offer to switch to the Gigabit X2, which promised up to 2G bps down and 250 Mbps up
-After going round and round with Xfinity support...I found out the Arris S33 modem will NOT work with the UP speed and would need to get one of their Xfinity Gateways.
-Bit the bullet and decided to rent their latest version...The XB8 Gateway. I setup the Gateway in Bridge mode...so I can still use my ASUS Router . (I have a mesh network with other ASUS routers throughout my house).
- Got it all setup and activated and starting seeing 900M to 1G bps down and 235 Mbps up. Hmmm... Why is the DOWN speed still low???
-Found out the XB8 has a 2.5G port that I should be using to connect to my ASUS RT-AX86U 2.5G port. Let me give that a try.
-Modem Shows port is 2500Mbps and Router shows "eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 1e) Link Up at 2500 mbps full duplex". COOL....that should work!!! NOT!!!
-Actually...with my router connected to the 2.5G Xfinity modem port, I'm getting SLOWER speeds then when I have the router connected to the 1G Xfinity Modem Ports.

You can see below (from spdMerlin on my router), where I switched service with Xfinity. Upload (Green) jumps up...and download is less than I had previously.
Then I switched to the 2.5G port on the Xfinity gateway...and you can see the dip in the download...to around 600 Mbps. Then I put it back to the 1G port..and it jumps back up to 900+ Mbps.

WTF.... Any ideas???

 

[degrub]

What do you get if you take the modem/router out of bridge mode while keeping the same physical connections ?
And, btw, use a PC with a 2.5 Gbit/s NIC to test direct connected to the Xfinity equipment, not the router so you don't run into router limitations.

 

[phillyaj]

What do you get if you take the modem/router out of bridge mode while keeping the same physical connections ?
And, btw, use a PC with a 2.5 Gbit/s NIC to test direct connected to the Xfinity equipment, not the router so you don't run into router limitations.

Yea...I'm gonna play with that to see if it's a limitation of the Bridge mode. I just don't want to use the Router portion of the gateway. I like my ASUS RT-AX86U and have mesh configured throughout my house. I just ordered a 2.5G ethernet adapter to check out the connection without the router.

 

[phillyaj]

UPDATE: Was chatting with a Xfinity Tech who claims he was able to get 1976Mbps to my XB8. So WHY does my router seems to be stuck at around 1G or less? I just ordered a 2.5G ethernet adapter to test without the Router. Kinda have a feeling it's going to work....then I'm stuck wondering what is up with my RT-AX86U and the 2.5G WAN port..

 

[degrub]

Double NAT does not usually cause issues for regular residential usage.

 

[AntonK]

UPDATE: Was chatting with a Xfinity Tech who claims he was able to get 1976Mbps to my XB8. So WHY does my router seems to be stuck at around 1G or less? I just ordered a 2.5G ethernet adapter to test without the Router. Kinda have a feeling it's going to work....then I'm stuck wondering what is up with my RT-AX86U and the 2.5G WAN port..

Is your AX86U setup for IPV6? If it is, try turning it off and then test your router for download speed. Setting up IPV6 on my AX86U (or now my GT-AX6000) with Xfinity cuts my download speed fully in half. I don't know why, but I'm not a techie.

 

[resmith45]

I had a similar issue but I have Ziply Fiber. Just upgraded from 1GB to 2GB. After they upgraded the hardware, I was still only getting a max of 1.2GB up / down on the Asus speed tests. The tech connected his phone to the WAN cable and showed me 2GB up/down.

What I found today, was I had to go into the Dual WAN config under WAN and set the Primary WAN to 2.5GB WAN (even though I'm not using Dual WAN). Now I'm getting close to 2GB speeds up/down.

 

[phillyaj]

So I went ahead and treated myself to a New ASUS RT-BE88U Router and Now I am able to get the speed I've been paying for. As suspected, the RT_AX86U couldn't it.