I am new to AbelCam and have been trying to connect from the same PC that I am running Abelcam webserver on (to check if it is working) but it always failed. localhost was fine but whenever I tried connecting using the external IP (the WAN IP of the ZyXEL router) it failed. I even tried turning off my Symantec firewall (not for long!!) but that didn't help. Finally after a week of trial and error I got it working - here are the steps and settings that are working for me.

First let's start with the Abelcam settings:
Configuration->Web Server Basic
Activated the checkbox for Web Server
I am using Host name localhost and port 8080 for both server port and external server port (don't know what the difference is to be honest). Clicking on Autohost gives you the external (WAN) IP of your router - you can use this in the next step but I've stayed with localhost for the host name.
(remember to save the settings).

Configuration->Internet
Clicking on Reset to Defaults gives you the settings from the Web Server Basic page. Here I changed localhost to the external WAN IP I found on the previous page. Not sure if this is necessary but as it is working now I'm not going to try changing it!! Remember to save settings again but dont't test yet, it still won't work.

Now you have to set up port forwarding on your ZyXEL router. All the information you need is at the website (very comprehensive for all routers): www.portforward.com. Forward port 8080 to the internal LAN IP of your PC e.g. for ZyXEL 192.168.1.xxx

Next is your firewall - you need to allow TCP/UDP traffic for the REMOTE port you defined in the Web Server Basic page e.g. 8080

Finally for ZyXEL routers (maybe others) - they normally don't allow loopback i.e. external IP to internal IP. By downloading the Zyxmon monitoring program from:
http://zyxmon.streamclub.ru/downloade.php
you can change this.
To get things running with Zyxmon you need to enter the settings for the local LAN IP address and password of your ROUTER, normally for ZyXEL IP 192.168.1.1 and password 1234 (why don't they just default these?).
Then click on the Telnet Client button and enter the command:
ip nat loopback on
Now loopback will be working.

Back to AbelCam:
Configuration->Internet
Hopeffully for Cam URL you see the entry you set earlier:
http://xxx.xxx.xxx.xxx:8080/index.html (where xxx.xxx.xxx.xxx is the external WAN IP Address of your router) - now click on TEST 3 and hopefully you get to see your webcam. Sorry if not. Don't know what else to suggest.
Cheers, Andy