VPN disconnects WiFi while attempting to connect

This is an issue I've had across multiple networks and multiple VPNs, so I believe this is an IOS issue. Whenever I attempt to connect to a VPN over a WiFi network, my device will disconnect, attempt to connect over my mobile data connection, then reconnect to the WiFi network. This becomes an issue because I use a network in a remote location that gets poor data reception, so I end up not being able to connect at all. This has happened with ExpressVPN, Nord, and Mullvad on both private and public networks.