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VPN Question

So here is the scenario, I work for a Point of Sale company and one of the things we support is a remote VON connection for the store owners to connect to their restaurants from home.

I’ve noticed in the past few months that there have been more users getting new modems and then not being able to connect to the store remotely any longer.

All of them seem to be related to having CABLE inet connections from home,

So to confirm that the connection is working fine I always connect up and have no issues.

So I’m wondering if there is some kind of weirdness going oinw with later DOCSIS modems ?

Anybody seen something similar ?

Could be a Firewall issue or possibly a blocked port

Check if they have proper IPv4 support if you are running IPv4. If the carriers are runnig some crap like DualStackLite with carrier grade NAT then you’ll need to take care of that. Where I live, the cable internet provider all don’t supply proper IPv4 connectivity.

Thanks for the feedback, it does seem strange that this seems to happen randomly but always after equipment replacement.

Of course I have to take the word of the ISP that nothing is being blocked but it does make one wonder.

If the carriers are running some crap like DualStackLite with carrier grade NAT then you’ll need to take care of that.

This is only a problem if the VPN solution you are using is IPSec based and doesn’t have NAT-T supported. If you can, switch your VPN to just being SSL based which doesn’t care about being NAT’d or needing to be punched out on UDP/500.

Could it just be something like there’s a firewall in front of your VPN server that was configured with all your user’s public IP addresses and when they get their new modems they get a new IP address so they are now getting blocked?