Wan drops from 1000 to 100

[magicool]

Hello,
Every few days, on my ASUS AC68U, the speed of Port 0 (WAN) drops from 1000 to 100. I can get it back to 1000 by unplugging the WAN cable, or by rebooting the router, or by rebooting the media converter from the ISP.
Any way to trigger an automated reboot of the router when the speed of Port 0 drops to 100?
Or any ideea why this happens?
Thank you!

robocfg show (when I get full speed):
Port 0: 1000FD enabled stp: none vlan: 2 jumbo: off mac: xx:xx:xx:xx:xx:xx
robocfg show (when I get 100 speed):
Port 0: 100FD enabled stp: none vlan: 2 jumbo: off mac: xx:xx:xx:xx:xx:xx

 

[joegreat]

Wrong cable for Gbit connection? See discussion here!

 

[magicool]

Cable is Cat5e. Works for a few days at 1000mbps and then drops to 100mbps. That is why, as a workaround, I need a script to reboot the router when link speed drops to 100mbps.

 

[sfx2000]

I would swap the cable out - and consider rebooting the modem - both end of the link have to agree...

OP didn't mention the modem, but some have an option to disable Energy Efficient Ethernet - if the modem has that option, might consider turning it off..

 

[magicool]

Fixed for now. I set the router to reboot daily and so far all good. It would have been nice to reboot only when link drops to 100mbps but I don't know how to do that.
Already changed the cable; I do not have user access to the modem (Huawei HG8240H).

 

[seanr22a]

Most likely cable problem. I had a 10m CAT5e to my 88U same thing happened speed drop from 1000 to 100 little now and when. Had to unplug cable or reboot.
I replaced the cable. The new one that happened to be a CAT6 but I don't know if it makes any difference with such short cable. The old CAT5e had no visible damage anywhere but it was the cause of the problem.