NOTE: There is a bit of geek-speak ahead here. If you are reading this and none of it makes any sense, it's very likely that it doesn't apply to your home Wi-Fi. These configurations are not common for typical home Wi-Fi networks.

How many networks can Circle manage at a time?

Circle only manages one network segment at a time, so for folks whose networks involve a less-common configuration, this is an important detail to keep in mind.  If your network has multiple segments, including guest networks, Circle will only be able to manage one of them.

How many subnets or VLANs can Circle manage at a time?

If you have configured your home Internet to have multiple subnets or VLANs, Circle will only be able to manage one subnet or one VLAN at a time. These are treated as distinct network segments by Circle, and traffic that flows through the other subnets or VLANs will not be seen by Circle. To manage any of the others, you will need an additional Circle to handle that network traffic.