1 ecobee keeps losing WiFi

I have 2 ecobee3 thermostats along with 3 sensors. The upstairs ecobee works fine, but the downstairs one keeps losing WiFi. I've reset it to fix it once, but upon trying that again today, it refuses to connect. I've double checked all the settings and they're all correct, I just can't figure out if it's a bad unit.

Just discovered it will connect to the guest network but will not connect to the main network.