Connecting by VPN to my RT-AC88U gives me access to primary and guest network

Hi,

I have looked around for confirmation to my two questions but ended up short.

1) I have setup my router with a primary wifi as well as a guest wifi.
2) When I connect my pc to either wifi I cannot ping the other (which I expected/wanted)
3) However when I login to my router via VPN (openVPN) I can ping devices no matter which network they are on.

My 1st question: Is it supposed to be as per point 3? That I can access all devices no matter their network when connected by VPN but not...

Connecting by VPN to my RT-AC88U gives me access to primary and guest network