@Virgo Thanks!

So I spent quite some time on it yesterday and finally got it to work! The issue was actually that my PPTP connection was not working, although it was showing in the VPN status. Still not sure what was wrong with it, but I created an OpenVPN one instead and it works fine! Speed is about half of what I was getting from PPTP (granted, not from when it was connected via the ER605 as that never worked), but it's still useable if I go for UDP.