Verizon Fios blocks pptp vpn connections

Question

I'm in the process of transferring from Optimum to Verizon but still have both internet connections active for a while - I wanted to check whether some of the problems which I've been experiencing are related to the internet connection or not.

In the process I've discovered I'm not able to connect to pptp vpn servers while using the Verizon internet connection. When I switch the connection to Optimum, pptp still works fine on the same PC and router. However other vpn connections such as OpenVPN and WireGuard work fine while using the Verizon internet connection. Not a big deal since pptp is probably obsolete and not recommended but still wanted to report this.

smith6612 · Accepted Answer

Are you using the Verizon router? My first guess here is there is some sort of subnet conflict between your router and the remote network while you're connected to the Verizon network. Could also be an ALG issue or an issue with McAfee Home Network Protection; The former which is not possible to adjust the last I checked, and the latter which I would recommend disabling if it's enabled in your Verizon account.

As for what Cang_Household mentioned, if you do have the ability to use a newer VPN protocol such as Wireguard, IKE/IPSec or DTLS tunneling,  that would be good to do.