Question:

I have just upgraded the firmware in my Vigor2830 router and now cannot access my Exchange webmail server, which uses https port 443, from the Internet.

Answer:

The latest firmware for the Vigor2830 (version 3.6.4) has added SSL VPN feature which also uses port 443.
You will need to change the default port to a different value such as 444.

Also you may need to change the default https management port from port 443 to a different value such as 444.

These settings are in:
“Web Access Control >> General Setup”

in “System Maintenance >> Management”