I have a 2860 upstairs linked by cable to an AP900 downstairs. In a separate building I have an AP700 in universal repeater mode connected wirelessly to the AP900. The LAN connection on the AP700 is connected to an Ethernet camera.

I can see the camera from any PC on its internal 192.168.1.x address but I cannot link to it via an external IP address (I have 5) with "Open ports" in the router set to forward the external IP WAN Alias to the internal camera IP.

However, if I substitute the AP700 with a Sonos Bridge, which connects wirelessly with the network in the house, and change nothing else everything works as it should - I can see the camera on both its internal and external IPs.

This makes no sense to me and I'm sure I'm missing something but I just can't see what - any suggestions welcome!

I may be wrong but doesn't the SONOS work in bridge mode not universal repeater? they may be the issue.

Yes I believe it is a bridge so I've tried the AP700 in station mode, bridge mode and wds mode - none of them work with the camera.

Today I tried connecting an Hauppage PCTV box (which I also access via another external IP address) through the AP700. I had exactly the same problem - I could connect to the PCTV via its internal LAN address but the external port-forwarded address would not connect and showed as "not responding" on port scanner websites.

On a whim I changed the wifi setting on the router and the AP700 to "long preamble" from the default "short preamble" and lo and behold the PCTV box could be accessed via the external IP!!!

I thought I'd cracked it and so connected the camera again through the AP700 - still no external connection

I'm going to try an AP710 and see if that makes any difference, although on the AP900 and I believe the AP710 there does not seem to be a "preamble" setting. From the PCTV result it would seem that everything is set properly to port forward but something in the wifi connection is blocking it. The question is what?

Well I tried an AP710 and my heart sank when I found I couldn't even see the PCTV or the camera on their internal IP addresses! This was worse than the AP700! (as an aside, although Draytek claim on their product website that the AP710 has a "client (station) mode" option as does the AP700 in fact this mode does not appear in the options available on the device).

I found a more up to date firmware for it on the Vigor.com site, installed that and then I could see the camera on its LAN IP but still no luck on the forwarded external IP.

As you can imagine I have been trawling the web and found many people with the same problem - port forwarding not working over a wireless link, not only with Draytek gear, mostly Netgear and Belkin.

Finally I found the answer! I had been using IP-MAC binding on the camera's LAN IP address - simply removing that and hey presto - camera once again accessible on external IP.

So port forwarding seems to work when IP-MAC binding is present over a wired Ethernet connection but it doesn't work over a wireless link.

I hope this saves others tearing their hair out as I have been doing for the past week!!

Good find!!