Forum Discussion
UDP port 4021 tmobile VS my alarm server...
It is unlikely the T-Mobile is blocking at the network level so it would be related to the router itself. The Envisalink uses UDP port 4021 for communication so the router is blocking that port, po...
According to their information, “ensure outbound UDP port 4021 and outbound TCP port 4022
are not blocked on the network.”
I ran a local port scan against the Nokia gateway the other day with Zenmap just to check for filtered ports. I found only 3 open ports 53/tcp, 80/tcp, 8099/tcp on 192.168.12.1. Given the use of CGNAT as the T-Mobile solution without using a VPN I would guess the blocking is pretty extensive. It does seem to put a number of limitations on the usage. Frustrating for many users.
I also used http://ports.my-addr.com/check-all-open-ports-online.php which is developed on nmap.
