By the way, I still think my personal modem/router/firewall is causing the problems, not the corporate proxy, as I have the same problem via mobile and my colleague does not experience problems at all.

What do you expect to happen on other ports than 8080 for http? will the proxy interfere as well?
Just curious, I will leave it on https anyway..

I tried https on port 443, it actually works. So now can access the domoticz webpage from outside my local network, great!

Must be something else, as a colleague has exactly the same setup and it is working for him... Also when I try via mobile on 4G, it doesn't work.

I like the HTTPS suggestion, will try that and come back here...

I didn't even know there was such a thing.. The java console says: Creating Application Cache with manifest http://myname-hidden.ddns.net:8080/html5.appcache (index):1 Application Cache Checking event (index):1 Application Cache Downloading event (index):1 Application Cache Progress event (0 of 532 ...

I've got a strange problem: I just set up Domoticz on a raspberry pi, and added forecast.io, next week I will get a smart meter and connect that too. I can connect from my internal network to the domoticz page on port 8080. However, when I enable a port-forwarding rule in my router (a ziggo ubee ...