cant install 8.3.4 server

[imackify]

I just upgraded to DSM 6.

Reinstalled Java 8.

Tried to install server 8.3.4 and i get the error "Port undefined configured for this package is either used by another service or reserved for system use. Please disable or modify the conflicting service, or contact the developer to modify the package configuration."

The closest solution i found when searching for this was a similar message with the port 9790 mentioned. So i tried all those steps (logged in SSH as root etc). Still same error as above.

I had version 8.1 of the server installed, and i didnt remove it but its gone now, so i cant just upgrade.

any ideas? im at a loss.

thanks