Asus RX-AX88U Pro - WAN Ethernet keeps degrading to 100mbps

[nathan951]

So this RX-AX88U Pro router P'N'P replaced a Netget R7000 Nighthawk with Asus firmware, which was running rock solid for years. I would get the occasional need to reboot once every couple months.

Fast forward to this router, I never have to reboot BUT for some reason the WAN port falls back to 100mbps from gigabit.

I know the first thing you're going to say is it's the cable, BUT the 10yo old router never did it, and just by unplugging and plugging the cable back in it fixes itself. You can see the last few times I've just unplugged the cable and plugged it, pluged back in and it would work again anywhere from 1-5days until i notice it is not working and unplug cat5 again

FYI, running merlin 3004.388.7

Speed test from my unraid server 4x/day

 

[Tech9]

this RX-AX86 Pro

The ports screen shot above shows a router with 2x 2.5GbE ports and single USB port. You perhaps have an RT-AX88U Pro?

 

[nathan951]

FYI I just ran: "ethtool eth0"

noticed: "Auto-negotiation: off"
Tried: "ethtool -s eth0 autoneg on"

but no change:

 

[nathan951]

The ports screen shot above shows a router with 2x 2.5GbE ports and single USB port. You perhaps have an RT-AX88U Pro?

ohh you're correct title and text changed

 

[nathan951]

I'm not sure if this is the best fix, but AI helped me generate this temporary patch in cron:

#!/bin/sh

# Check WAN interface speed
SPEED=$(ethtool eth0 | grep "Speed" | awk '{print $2}')

# If speed is 100Mb/s, reset WAN connection
if [ "$SPEED" = "100Mb/s" ]; then
    logger "WAN speed is 100Mbps. Renegotiating connection..."
    
    # Bring down the WAN interface
    ifconfig eth0 down
    
    # Sleep for a few seconds to ensure the interface is fully down
    sleep 5
    
    # Bring up the WAN interface again
    ifconfig eth0 up
    
    # Log the action
    logger "WAN interface reset. Checking speed again..."
    
    # Optional: recheck speed after a short delay
    sleep 5
    SPEED=$(ethtool eth0 | grep "Speed" | awk '{print $2}')
    logger "New WAN speed: $SPEED"
fi

 

[Tech9]

There are reports here and there of this happening, perhaps some incompatibility between modem and router ports, some people use a switch between them and seems like it solves the issue too. Trying with a new cable won't hurt as well. The script is Band-Aid solution with service interruptions.

 

[nathan951]

There are reports here and there of this happening, perhaps some incompatibility between modem and router ports, some people use a switch between them and seems like it solves the issue too. Trying with a new cable won't hurt as well. The script is Band-Aid solution with service interruptions.

Thanks for your response.
Yeah, I have tried two cables, one being the original cable that worked with my previous router and the other one being the brand-new cable that was included with the router.

Yes I do agree with you this is band-aid. I'm unsure if there's another way to make it automatically renegotiate if it degrades to 100mbps or some other setting I'm missing.