@John1234 Thanks so much for your advice. Unfortunately I have been unable to insert the switch between my bridged router and the Google Nest Wifi without losing internet access. Possible...

@Briston1969 Adding a bit more context here. I have been following, or trying to follow, the instructions below (substituting my ISP's reported VLAN ID - 101 - for the one mentioned there)....

The manufacturer of my (third-party - Google Nest) mesh wifi system has suggested that I use a managed network switch to "remove VLAN tagging" between my modem and their router. So I have bought an...