I have a Shaw Blue Curve modem/router device.

On Jan 12 or so I set up forwarded port 443 to a server I had running for my office VPN. The next day when trying it from outside, it wasn't working.
Then for two weeks I had other more important things to do. I tackled it again yesterday, first thinking that maybe I never saved the setting back on the 12th. So I logged in to the management page and saw that the setting was configured.

Then I decided the problem must be with the server (which had worked for a year already at another location) and that I would have to check over the settings on the server.

Well everything looks correct so I go back to the Blue Curve management page. I delete the configured forwarded port. I try to re-add it, it doesn't work.

Try as I might, I cannot configure a port to forward to my server. Whether I try 'manual' or use one of the pre-configured game options. The error message suggests to 'try again later'.

I read many pages of posts/questions on the net from other people with the same problem. Some here on Shaw support, some on Reddit. The only answers seem to be reboot the modem or factory reset the modem.

I rebooted it remotely. It didn't help. I power-cycled the modem (unplugged it, waited, reconnected it). Still doesn't work. I haven't been willing to reset it yet.

I did find one interesting clue this afternoon though: It turns out I can forward ports to the physical machine that this server is hosted on. I just can't forward to the virtual machine for some reason.