Can't Connect to PPTP VPN on any device

Pooriya77

After I replaced my old router with the VMG1312-T20B I can't connect to PPTP VPNs for some reason.
it gives an error about something called GRE
can't find the firmware update on the website either.

Current Firmware Version: V5.30(ABIH.0)b3
Current WWAN Package Version: 1.18

Hummel

@Pooriya77,
Do you want to use VMG1312-T20B as PPTP VPN server or do you meet the connection problem to connect your client behind the router to the PPTP VPN server? Do you remember how you configure your old router to make it work?

Pooriya77

@Hummel,
I'm not sure about what your asking, I'm just noticing that the VPN I used every day on my pc is not connecting anymore after changing my router (same thing on my laptop and iPhone). 
Didn't configure the old router at all really I just remember turning off WPS, everything else was on default. 
If I have to guess it has something to do with the router's firewall and turning it off messes up with some of my other programs.
and btw this is only happening for the PPTP, the L2TP works fine.
Here's the error it gives.