I have two networks:-

Net 1 - 192.168.1.x - gateway is a Watchguard Firebox (internal IP 192.168.1.1, external IP 192.168.0.53)

Net 2 - 192.168.2.x - gateway is a Vigor 2910 (internal IP 192.168.2.1, external IP 192.168.0.54)

Both routers go through the same Vigor 2800 to the internet (IP 192.168.0.2)

Here's the problem:-

Computers on Net 2 cannot FTP using browsers (IE, Firefox, Chrome) - BUT can FTP using the FTP command in a command prompt.

Net 1 does not have this problem.

I believe that browsers use passive FTP, whereas the FTP command uses active FTP.

Could it be a problem with the 2910 blocking passive FTP (can it do that?), or could it be a problem with double NAT between the 2910 and the 2800 (even though it works for the Firebox and 2800)?

Any help would be appreciated.

Thanks.