base 100T network or better?
Do your router also have a DHCP?
What is your router IP? many set the router IP to ***.***.***.1, LMCE does the same and will crash the IP, but you can set either manually.
That could be a reason?
I had that "problem", I set my LMCE to ip ***.***.***.10 and 100 and set the DHCP IP range from 20 to 99 for LMCE devices (just to make sure, I have equipment on 1, 2, 3 and 4).
My core has dual gigabit.
I dont have my router plugged in at all. My setup is as follows:
Cable Modem --> LMCE --> switch --> Other PCs