Thanks to @DisposableHero
Github master file has been changed to accommodate IPv6 IP addresses.
New installs after the date/time of this post will be set up for IPv4 and IPv6 IP addresses.
https://github.com/ProAviaAZ/phpvms_5.5.2.72
Previous installs can update to allow IPv6 addresses by running the SQL queries below. Both are needed.
25 chars will not be enough to store v6 addresses. It should be at least 45 chars to avoid errors.
So during install, setting ip related column length as varchar(45) may solve future issues with new members using ipv6. Also for current users of your release, running simple sql queries may help to solve this little problem.
This is for the pilots table:
ALTER TABLE phpvms_pilots CHANGE lastip lastip VARCHAR(45)
https://github.com/ProAviaAZ/phpvms_5.5.2.72/blob/master/install/sql/install.sql#L336
Same logic applies to the sessions table too;
https://github.com/ProAviaAZ/phpvms_5.5.2.72/blob/master/install/sql/install.sql#L471
ALTER TABLE phpvms_sessions CHANGE ipaddress ipaddress VARCHAR(45)
Direct manipulation via phpMyAdmin on the above two items is also possible.
Additionally, any Modules that list an IP address will need their associated table changed.
For example, kACARSII has a sessions table (kacars_sessions) that includes ipaddress. So, varchar for ipaddress needs to be changed from 25 to 45 there also.
As always - BACK UP the database first. Only you are responsible if the above doesn't work for any reason.