I also have a RT-AC88U. My LAN ports 1 - 8 are all fine, other than 5. I don't have anything plugged into 5, but noticed under system status on the main screen the router was showing 100Mbps! Plugged something in, didn't work. All other ports reflected the status correctly immediately on that web page, and passed traffic. SSH into the cmd line, and robocfg show also stays down on port 5. BTW, I am running the latest stock 184.108.40.206.385_20631 firmware. Very happy with the router, and with this firmware, rock solid, apart from the annoying syslog spamming that has been there for a few firmware versions (I've reported it, let's see): https://www.snbforums.com/threads/portslinkstaus-0-after-ac88u-3-0-0-4-385_20585-update.64755/ I believe this bug is fixed in the Merlin firmware. Interestingly, this spamming is I believe linked to debug checking the status of the Ethernet ports (I think I read that somewhere, cannot be 100% but thought I would mention it), so wonder if Asus are aware they are flaky? My entries were: kernel: portsLinkStaus=0 but now they are: kernel: portsLinkStaus=1 Not sure if that is picking up the now dead port - cannot be sure of timing. If I move the Ethernet cables to other ports, I can also get it to a value of 3 - anyone know what the numbers mean?