Help please network issue Rpi 512mb version


Installed osmc on an rpi model b 512 on a usb Stick install ( Think it sais version 2015.9.1 ) The top one on the self installer . Everything works fine when plugged in a switch direct to router but if I move to upstairs via a switch plugged into a power line adapter it shows not connected. I’ve tried direct to powerline as well with no joy. If I plug my laptop into switch via power line it works fine. Any ideas you clever lot… oh also tried setting the ip manually. Either way static or DCHP it shows mac address and random 169.x.x.x. ip. Any ideas you clever lot.
Thanks for any help.