Only one client can connect via wifi


I have encountered a strange issue where my Homeassistant running on raspberrypi 3 over wifi can only be connected to with one client at a time. So for example if I navigate to homeassistant:8123 in a browser on a PC, I can connect, but then my iPhone app or a second PC will be unable to connect and get an ERR_CONNECTION_TIMED_OUT error. The connection between the router (Ubiquity Dream Machine) and raspberry pi is very solid tx/rx > 50Mbps. Interface is super responsive on the one device that can connect. I completely shut down the PC with a good connection last night, at which point I could connect to it with a phone, but then not with the PC once rebooted.
I have tried Test-Netconnection on the local address which fails as if there is no host at that address. I have multiple ubiquiti APs if that makes any difference. This is very annoying please help!