Server parameter in CALL "*web/sftp;receive"

[Peter.Higgins]

Server parameter in CALL "*web/sftp;receive" is confusing me somewhat. 
I recently implemented a client with Id/Password where the domain:port only worked as domain;port. (Delimiter = Semi-Colon)
The next client using a cert only works with domain:port.
Is there a way to know when to use a certain delimiter in the domain sent? 

[Devon Austen]

Using ; should always work.

What is the error you got when using ;?