Why does my internet network keep telling me I have "limited connectivity"?

Interference from something. Move cell phones and cordless phones far from the router and the path between the router and computer. Phones operate on 2.1 GHz, as do microwaves. It would also be someone upstairs/downstairs that's causing this. Move the router if you can to first test this. If you can't move the router, switch the SSID channel from 6 to 1 or 13 and see if that helps.