Windows 10 vpn

Occasional Contributor
Hi!
At our company we have just deployed a Vpn via Windows server 2019, but i get a error message about the GRE protocol but it works as soon as i connect with a sim card but when i use a hotspot from My galaxy note 10 it gives me a error about GRE? I havet tried diffrent phones but it dosn't make any differens?
2 Replies
Hi,
which protocol does that VPN server use?

@HotCakeX  We are using a PPTP VPN