If you have a separate modem and router, I would first plug the suspect unit directly into the modem as a test, and then reset the modem. If you can make your calls then, I would somehow suspect the router or settings -- despite the other unit working through that same router.
It could be the box. I would reset the problem OBi to factory defaults, and then set it up again.
You could delete that OBi from OBiTalk, and then Add A Device. You might try a shorter procedure where you set the password back to admin, as it will be on the unit after factory default, and then see if the update gets everything going. I don't know if somebody has posted a process for that. But deleting the device on OBiTalk, Reset device to factory default, and then Add A Device would be the most comprehensive thing. If that does not fix it, I would replace the unit.