Connect Ethernet extender from router in downstairs to upstairs bedroom.
Connect Ethernet extender from router in downstairs to upstairs bedroom.
It entirely depends on how they've been wired inside the wall. If the two wall-sockets are directly connected, then yes, and if they aren't, then no. EDIT: I forgot to mention that you can buy an Ethernet-tester to check this with, they're not expensive devices. Here is an eBay-link to an example one -- you can probably find similar ones even in local stores.