Java.net socket exception

[Bamboozled]

Hi all,
I'm using AndFTP to connect to my Synology NAS.
Using wifi I can generally connect without a problem, but using 3G/HSPDA I have only successfully connected once (and that was at home when testing). Every other time I get an error "java.net socket exception the connection was reset"
Is this my fault, my mobile provider's fault, my internet provider's fault, or my NAS's fault?
I'm afraid I'm a bit of a novice at this stuff, so don't really know how to test it. Any guidance would be welcome.

Thanks.

[support]

Could you provide a testing FTP account to support(at)lysesoft(dot)com?

I would say it's a problem with mobile provider. It could block ports.