@TP-Link 

Sorry for my late reply, and thank you for the guidance. No parental control profile, my network at the time consisted of my decos (2), with the main deco plugged straight into my internet (no modem). I was using the built in firewall in windows 10, no other active antivirus (Malwarebytes for occasional scanning).

I ended up putting my old Asus router back, so my topology now is Internet --- Asus --- Deco ~ Deco, and my VPN works as it did before. I think I'm gonna stick with this setup for now. If I end up ditching the Asus router later on I'll be sure to try disabling my firewall first thing.

Thanks again!