RAXE290 regularly forgets ethernet LAN connection

Of the many things I've tried, the only thing that fixes this is a router reboot.

PC's ethernet is not put to sleep as part of a power plan.  It's a desktop, and isn't setup that way.

Even if it were, I wouldn't a PC reboot, or 

ipconfig /release

ipconfig /renew

wake it up? Neither helps here.

This changed exactly when I changed routers. The old one had flaky wifi, but the hardwired connections were flawless, this router is the opposite. 

Ethernet goes away while I'm working on the PC

I tried swapping cables, but it made no difference. It works after a router reboot, then the router shuts down the port after some time.

And I checked router with the nighthawk phone app. It sees the PC as disconnected.