VPN Client works with some ISP networks and does not work with some ISP networks

[anupamsworld]

Hello.
I have installed both VPN server and Client in same machine. Enabled VPN over ICMP, VPN over DNS checkboxes.
I am able to connect VPN server from client in some ISP network but unable to connect in some other ISP network, with unaltered Softether server and Client settings.
I am from INDIA.

Example:
Few ISPs with which connection works are Vi, Airtel etc.
Few ISPs with which connection does not work are BSNL, Some Broadband ISP, etc.

Please help.

[solo]

I have installed both VPN server and Client in same machine...

No need to read any further as this is usually unworkable or inconclusive.

Install them in machines running on separate ISPs.