power gallery has no restriction on using an IP address for the MySQL Host.
the only restriction on entry is that none of the connection fields are left blank.
If the IP Address is not working, then it means the IP address is not the correct address to enter when connecting to the MySQL Server.
very few hosts actually use the IP Address for the MySQL Server name, it is not a common practice. you should contact the host to determine the correct address that should be used for connecting to the mySQL Server