I have a spectrum modem with no wireless capabilities. I hooked up a TP-Link AC1200 to the modem and plugged my pc into the router via Ethernet. I cannot get Internet from the router via Ethernet or WiFi. I could only get a constant connection for about 20 minutes when I copied the MAC address from the router and manually entered it and then changed the operation mode to access point. When I changed it to access point, I couldn’t access the configuration page via default gateway. I had to reset the router. I have little idea what to do