I have "Three" as an Internet Service Provider. I am using their mobile 4G+ Hub (i.e. connects to the Internet with cellular). It works fine, but the WiFi range is very limited in the house so wanted to add the Google Nest WiFi.
However I don't see there is a "modem mode" on the Three router configuration. Will the Nest WiFi router still work with this situation?
The Nest WiFi Router needs an Ethernet connection to the internet. If the 4G+ Hub has an Ethernet port for the inner network, the Nest WiFi Router's WAN Ethernet port can connect to that, and will very likely work just fine even without the 4G+ Hub being in "modem" (bridge) mode. There is a chance it won't, but if that turns out to be the case, keep the packaging and receipts for the Nest WiFi system so you can return it.
I just wanted to jump in real fast to see if you saw MichaelP's reply and to see if you still needed some help on this or if you were able to get it sorted out. If you are still needing some help, just let us know and we'll be happy to continue helping.