LaserJet Pro 400 MFP not working on the network port that works HELP !!!

I have a new LaserJet Pro 400 MFP (M425dn)    USB works fine.  When I remove the USB and plug it into the network Port no network can be found - It doesn't pick up any activity.  So I test the network with my laptop ( connectivity is confirmed ).
The network port is working properly- I plug in the LaserJet Pro 400 MFP (M425dn) and restart it -  no network activity. I tried several ports in the front office and the printer can't connect to the network.  BUT HERES THE FUNNY THING .  If I take the printer to the back room where the router/switch is-  and plug it directly into the switch
( the same port as the front port )   it works !!!!!     so why doesn't the printer work at the front office network port,  where all the other devices work just fine using the same port ?  But it will work, at the  router/switch  using the same port  lol    this is drving me crazy  

 any help ? ? ?