Ok, to preface this I live in an apartment complex with an access point in my living room. I was struggling to get a decent connection in my bedroom (farthest from the living room). We bought (2) AC1200 Range extenders. we set them up in the most direct line of sight path to my bedroom. all is well. today, I set my PC up (no wifi card, only ethernet) in my bedroom. I plugged the ethernet from the range extender located in my bedroom into my PC. Voila, it worked. I was able to get ~80Mbps down, with 5ms latency. Super good. I was able to play a single online match to test the strength, then started on some homework. After probably 30 minutes (since initially plugging into the extender) my internet connection has disappeared. My PC cannot connect to the Internet. "The default gateway is not available" is the error I get when running Windows network diagnostics. The internet connection is fine, my laptop is still connected wirelessely. 

I used 'IPCONFIG' in the command prompt to find the gateway and try to ping it, to no avail. What steps should I take next? I don't want to run an ethernet cable through the apartment.

thank you