Validate URL on iOS for multi-part URL

Question

We're (me, a colleague and an outsourced dev) building an iOS webDav navigation App which we believe is having trouble validating a URL.

We're accessing a webdav server via the app. One of servers which is https://webdav.microdigit.org.uk/test/ works perfectly.

However our main server which is https://vpn.westbuckland.devon.sch.uk/webdav/ doesn't work.

It seems to be due to the extra dot in the URL but we're not sure.

This is our current expression:

 NSString *myregex = @"\\bhttps?://[a-zA-Z0-9\\-.]+(?::(\\d+))?(?:(?:/[a-zA-Z0-9\\-._?,'+\\&%$=~*!():@\\\\]*)+)?";

It just seems odd that the app will connect to a standard length URL such as https://vpn.something.com/ or even starting from a subfolder such as https://vpn.something.com/webdav/ You can then go one more and add another "dot" to the URL such as https://vpn.something.org.uk/webdav

However when you go one further it will connect to https://vpn.something.edu.org.uk/webdav/ but when you start trying to load a file or navigate the file structure, it reports a 404 in the debugger as if the files are not found.

Is it the extra dot in the URL? It seems to be the only thing we can think of. Our outsource dev has been pretty good so far in debugging most of our code (which was a purchased fully licensed base) but we're now reaching the end of the road. If anyone believes it is the regex expression. What would someone recommend we use instead?