Troubleshooting · Plain-English answer
When a VPN is connected, your device sends all traffic into the tunnel by default, including traffic meant for printers, media servers and casting devices on your own network. Those devices become unreachable. The fix is an allow LAN setting, which keeps local addresses outside the tunnel while everything else stays protected.
A VPN's job is to route everything through the encrypted tunnel, and everything includes the traffic that would normally take one hop across your living room. Your print job or cast request gets sent to the VPN server instead of the printer, and the printer never hears about it.
Device discovery suffers even more, because the broadcast messages that let apps find Chromecasts, speakers and smart home devices do not cross the tunnel at all. The devices are fine, but your phone or laptop has effectively left the local network.
The clean solution is a setting that exempts local network address ranges from the tunnel, so traffic to devices in your home goes directly while everything bound for the internet stays encrypted. ROOT includes an Allow LAN option for exactly this, and turning it on restores printers, casting and file shares immediately.
On shared or public networks, leave it off. The same setting that lets you reach your own printer would let you reach devices on a hotel network, and them reach you, which is not a trade you want away from home.
ROOT VPN is free to start with unlimited data, no card needed, and no activity logs.
Get ROOT VPN, free