I have run into the issue with the UniFi APs. I believe an update along the line disabled "B" by default. I had a client whose son set up and manages his Uni-Fi deployment. He called not long after we installed some wifi iTach units saying they stopped working. Tech support was quick to let me know what to check on the UniFi software. I had him tell his son to log in and enable 802.11b, and boom, it worked again.

I just asked Eero chat support about 802.11b, and they said it does in fact support it, and it is not disablable in the software. I made that word up, so there. So if it is still a problem after trying DHCP reservations, manual DNS entries, etc. let us know.

Have you talked with GC tech support? They have some pretty geeky guys there and I would be surprised if they have not tested EERO yet. If you have, and they have tested and that is the answer they gave you, update your first post to tell us so. :)