All you need to do here is plug the Linsys hub into the at&t router.
I’m not sure of the model, so am not sure if on the Linsys side you have DHCP setp, or
if you have hard coded IP addresess on each item connected to it.
If it is DHCP, turn this function off. Once connected to the router, the DHCP range set up
on this will pass through to the hub allowing the same IP address range on both networks
Alternatively try to remove the Linsys altergether, assuming coverage is OK, and just have everything
connected to the router. I take it you have already tried this, however.
O, you may need a crossover RJ45 cable to go between the hub and router if the ports
aren’t auto negotiating, or you don’t have an uplink port which is switchable.
As far as your wife, what VPN client? If using native windows client, check the properties of the connection, on the networking tab, check properties of tcp/ip, click advanced, and clear “use default settings of remote gateway”, see if she can print