how to play PBE with a VPN on?

I can play the main game just fine by adding a split tunnelling exception for the game's EXE and the riot client but for some reason the PBE is giving me login server errors. As far as I'm aware the PBE doesn't use a separate client anymore so I don't see why this is the case. I need my VPN on due to my country's heavy restrictions on internet usage so I'd really like to be able to play PBE with my VPN on.
Thanks.

For reference I'm using Proton VPN and I've added basically every EXE I could find in the riot games folder to the exception list with no results.