Need to unplug and reinsert cable into router to restore transfer speed

[Hobbsanddog]

I recently upgraded to the ASUS AX11000 pro.   I'm set up using PPPoE with a Bell Canada Fibe Gigahub modem with Fibe 1.5gb service.   

I have a cable running from the 10gb port on the gigahub modem to the 2.5gb WAN port on the ASUS router.

When at full speed the router pulls 1.7gb data download rate.  Daily the download speeds on the router drop to 900mbps and sometimes I've seen it drop to 50mbps.   The fix is me unplugging the ethernet cable from the back of the router (the 2.5gb port) and plugging it back in.   Speeds then jump back up to 1.7gb.

Does anyone have any clue why this is?   Is there a setting I should be applying on the router to fix this?  Is it a bad cable?

I have QOS turned OFF.  Running the latest firmware on the router and modem.

[jzchen]

Packet loss may cause the devices to throttle speed.  I think you’re right in suspecting cable quality.  Is there a reason you don’t match the 10 Gb port on the Bell hub to the 10 Gb port on the AX11000 Pro?  Although not noted I do suspect the 2.5 G port can be used as a LAN port.  What ethernet speed are you running on the LAN side?