Document upload and firewall

Hi - hope someone can suggest a fix for this.
This is a new installation of suitecrm on an external server - it’s very nice I have to say - well done!
However, I can upload a document ok from home but not from within our network in work. Firewall issue? I get a connection reset error.
The network is an ageing SBS2003 with a draytek vigor router. Is it necessary to open a port on the router for the document upload to work? Hopefully it’s not IIS causing this.

Thanks in advance for any suggestions
Cheers
Jim

Resolved this issue myself - in case anyone else has this issue, the problem was the firewall on the router - switched off firewall and document upload was successful.

Now to install new router as it has been playing up anyway!
Cheers
Jim