I finally managed to connect mine by allowing the following permissions
on Google Home app.... microphone, camera, contacts, location, nearby
devices, phone. The only permission I did not allow was notifications.
Same issue with me. Google Nest Hub 2nd Generation worked fine with
fibre cable broadband but will not connect to Zyxel NR5103EV2 5G NR
Indoor Router. Samsung tablet, Samsung phone, Xiaomi phone, Lenovo
Thinkpad, Chromecast with Google TV, Eufy doorb...