Thanks for the additional info. With this setup, your PC connected to the old router is on the WAN side of the pcWRT router, while the PC connected to the pcWRT router is on the LAN side. With Pia running on the pcWRT, the PC connected to the LAN side is tunneled to Pia’s VPN server. Therefore, it cannot see the local network on your old router.
You can add this entry to the “Split Tunneling” section on the VPN client settings page: 192.168.1.0/24
And yes, if you set a VPN connection to auto-start, the VPN will auto-connect on router reboot.