RT-AX86U 2.5GB Port not working

[eusriso]

I have a RT-AX86U router used in conjunction with an Arris S33 cable modem. My ISP is Shentel. The modem works okay with the router when plugged into the 1GB WAN port on the Asus Router when using the 2.5GB port on the Arris Modem. When I plug into the 2.5GB port on the Asus Router it does not work from the 2.5GB Arris modem port, I get msg that network cable is unplugged. I have gone into the Dual WAN section and changed the primary WAN from 1GB to 2.5 GB. I have tried using CAT 5E cables and CAT 6 cables. I have tried with DUAL WAN off and on. I have WAN aggregation off on the main WAN page. Any suggestions on how to get the 2.5GB port to work? Note: I am using Merlin Firmware: Current Version : 3004.388.7

 

[bennor]

Did you reboot the router after applying the change? Did you try rebooting the Arris modem after applying the change within the router? You might have to power off the router for 10 to 15 minutes as well as a troubleshooting step.

Another troubleshooting step, have you checked or confirmed that the 2.5GB port works with local LAN clients?
With the Arris modem connected to the router WAN (1GB port). On the WAN > Dual WAN page set Dual WAN to OFF. Set Primary WAN to 1GB WAN. Select the Apply button. Then connect a local network client to the 2.5GB port and check for connection.

Normally for WAN on 2.5GB port all you would have to do is set WAN > Dual WAN > Dual WAN to OFF, then change Set Primary WAN to 2.5GB WAN. Then select the Apply button. Then switch the broadband/Ethernet cable from the WAN 1GB port to the 2.5GB port on the router.

And just in case. Are you running any addon scripts? If so which ones?

 

[eusriso]

Did you reboot the router after applying the change? Did you try rebooting the Arris modem after applying the change within the router? You might have to power off the router for 10 to 15 minutes as well as a troubleshooting step.

Another troubleshooting step, have you checked or confirmed that the 2.5GB port works with local LAN clients?
With the Arris modem connected to the router WAN (1GB port). On the WAN > Dual WAN page set Dual WAN to OFF. Set Primary WAN to 1GB WAN. Select the Apply button. Then connect a local network client to the 2.5GB port and check for connection.

Normally for WAN on 2.5GB port all you would have to do is set WAN > Dual WAN > Dual WAN to OFF, then change Set Primary WAN to 2.5GB WAN. Then select the Apply button. Then switch the broadband/Ethernet cable from the WAN 1GB port to the 2.5GB port on the router.

And just in case. Are you running any addon scripts? If so which ones?

I have tried rebooting the Arris Modem and the Asus Router. I did not try powering off the router for 10 to 15 minutes, I will try that next. I tried using the 2.5 GB port with regular lan client and it did not work with two devices (Primary WAN set to 1gb). I am not running any add on scripts.

 

[bennor]

How is the router configured? For Router mode or for some other mode like AP? How is WAN configured? For Automatic IP or for some other setting?

No issues with an RT-AX86U Pro using the 2.5GB port, made a post a while back about switching from 1GB to 2.5GB port and how the Asus-Merlin firmware shows the difference:
https://www.snbforums.com/threads/ax86u-pro-testing-with-2-5gb-wan.89682/#post-902754

There is an Asus support article about switching to 2.5GB for WAN:

[Wireless Router] How to set 2.5G port as WAN type? | Official Support | ASUS Global

 

[bbunge]

Your ISP likely assigns WAN IP addresses based on the MAC of the router. Switching from the 1 GB to the 2.5 GB changes the MAC address the ISP sees. So, getting a new WAN IP address may take time for the ISP to notice the old port is disconnected and a new address needs assigned. Check the Internet Status/Lease Expires to see the DHCP renew time.
Or, Factory Reset with Initialize the router and set it up with the cable to the modem connected to the 2.5 GB port. Should work. A CAT5e cable should also be good but I would use a new cable and make sure it snaps into the Ethernet port securely.

Should be a pretty nice weekend in the Alta Vista area.

 

[eusriso]

I tried all of the advice given so far, resetting (hard and soft), waiting to see if the ISP picks up the new mac address. I even tried switching back to the ASUS Firmware. Nothing works. The 2.5 GB port does not recognize anything - when plugged into cable modem (when set to 2.5 GB wan mode) or laptops, a 2.5 gb switch that I have when set to 1 GB wan mode. No lights flash to indicate that it detects a cable plugged in. All of the devices work on the 1 gb ports including the 2.5 gb switch. Any other ideas? I am not quite ready to upgrade to WiFi 7. I am located near Alta Vista ....

 

[L&LD]

Have you tried a different cable (Cat5e or better)?

Have you selected the type of port (WAN/LAN) you want to use?

Try also an electrical reset. Unplug all network equipment from AC wall power, leaving the power buttons in the on position. Wait for a minute or two, then power everything back up.

 

[bennor]

The 2.5 GB port does not recognize anything - when plugged into cable modem (when set to 2.5 GB wan mode) or laptops, a 2.5 gb switch that I have when set to 1 GB wan mode. No lights flash to indicate that it detects a cable plugged in. All of the devices work on the 1 gb ports including the 2.5 gb switch.

As others suggested, make sure to troubleshoot by replacing the ethernet cable.
While rare its possible the port is bad or the wire contacts have become bent. Inspect the port itself to see if the wire contacts are bent or if there is debris in the port preventing proper contact.
To confirm, you are not running LAN client devices through any sort of extender, wall plate connector, coupling, or adapter/connector prior to connecting it to the 2.5GB port on the router.

 

[bbunge]

If the router is under warranty it is time to talk to Asus. My AX86U was a couple days out of warranty when it went wonky and they replaced it. Or it is time to look into an AX86U Pro...

 

[eusriso]

So I forgot that my MSI RADIX 6600E has a 2.5GB port that can be configured for WAN or LAN. I switched out routers and the MSI 6600E worked fine using the 2.5 GB port configured as WAN connected to the S33 cable modem using the S33 2.5GB port. I assume the port is bad on my Asus router. I bought the AX86U shortly after they came out. Time for a new router.