Just upgraded phone to Samsung S20 FE 5G UW. Updated it to the most recent software. And now my VPN using PPTP is no longer working over cellular data (5G/4G/LTE). My previous phone (Razer 2) was working with no problem and I was able to access my home VPN over PPTP. Even switching hotspot on the S20 FE and trying to connect to the VPN with the Razer, it will not connect. However, if I have the S20 or the Razer on a wi-fi network (outside my home) I am able to connect to the VPN with problem. I have isolated this issue to the cellular data.
This problems seems to have been an issue back when 4G LTE was introduced and many users in the past reported this. The VPN server I am using is my home router and I know is working fine. And occasionally I just need to grab some stuff when I am away from home. Now my hotspot is useless for this purpose, if my phone itself can not establish a connection to the VPN. Logs show it hits it, but times out.
It is my believe that any phone that is to work with their 5G network, its being put behind a NAT that is not allowing for PPTP passthrough on their network. Which is again causing this issue for early 5G adopters.