Try completely reinitialising all network states.
Run the following commands in an elevated (run as Adminstrator) cmd shell:
Reset WINSOCK entries to installation defaults (reboot required):
netsh winsock reset catalog
Reset TCP/IP stack to installation defaults:
netsh int ip reset reset.log
Reset Firewall to installation defaults:
netsh advfirewall reset
Telnet is a remote connection tool similar to SSH, but without the security of SSH. It uses client/server model - a telnet client connects to a telnet server using TCP port 23. Due to lack of security usage of telnet is discouraged in most situations, and firewalls routinely block port 23 to prevent incoming telnet connections.
In Git, locations in the form of [user@]server:path are interpreted as SSH addresses (and the 'clone' tool literally runs ssh [user@]server in the background).
By default, SSH connects to port 22/tcp, which is the standard SSH port. Git does not change this, and BitBucket's SSH service likewise expects connections on the standard port 22/tcp.