On my X55, which is serving as my main unit, there are 3 ethernet oprts.  One is connected to my FIOS gateway/modem.  I have one ethernet port connecting to an 8-port switch, and it seems to have no problems.  I tried to connect my PC to the third ethernet port on the router, and it keeps dropping the connection (doesn't reconnect unless I unplug the cable for a few seconds and plug it back in.  I moved the PC to a port on the switch and have no issues.  I also tried plugging my Tapo H200 hub into that port and it also drops out and won't reconnect.  If I plug the switch into that port, it also drops out.