Hey @wonder95! I’ve moved this post over to our Video Doorbells board so more neighbors can see and make suggestions on it. It sounds like you’ve done quite a bit of testing on your own and with support.
Being that the device connects to a hotspot, hardware is ruled out. Great suggestion on using another mobile device @Eagle328! This can sometimes help when setup is failing for seemingly no reason.
As you’ve completed most standard troubleshooting steps, the next best thing to try would be to simplify the network by unplugging the extenders. This will ensure the signal is not bouncing around different access points while trying to maintain a secure connection with the Video Doorbell. Try also creating a guest network as it will rule out any network settings.
Let us know how this goes! 