Unable to connect two devices at same time on Nighthawk MR1100

I have a Nighthawk MR1100, using ethernet only. Running ethernet out, into standard TP-Link ethernet switch. If one device is connected, the second device does not have access to internet. It shows "connected", but the data does not transfer, pages do not load. If I reset and use the second device, then the first one loses internet, so it is not the specific device.

How can I solve this? Thank you