We have a problem with outgoing FTP traffic going through our ISA 2004 server from one of our remote sites. It works absolutely fine from our main office, but when the traffic originates from our regional office (we connect to their Pix router via a VPN), it fails every time. The error from her workstation is "Windows cannot access this folder. Make sure you type the file name correctly, and that you have permission to access the folder. Details: the operation timed out". The user has a Windows XP PC but Windows firewall is switched off. There is a rule our firewall to allow access from all our subnets (including those from our regional office), so this should be applicable to all no matter what their location, however as a test I created a new rule specifically for the regional office subnet, which failed. I also started logging on the ISA server, while the user tried this operation again, and the message stated that the protocol was 'unidentified IP traffic' and the action was 'closed connection' (the source network was confired as 'internal however').
The guy who looks after the PIX is away at the moment, but I was informed by others that it is not configured to block anything (indeed if it was, there would be nothing hitting the ISA server). Something seems to be distorting this traffic when it comes from the remote site, and I don't know what it is.
Any thoughts?