This may work but I am not 100% sure.
First off, if you have never edited the config file read this,
https://vborg.vbsupport.ru/showthread.php?t=308457
Assuming you are using VB 4.2.X (and the config.php file from VB 4.2.X) find this line near the end of the file:
Code:
//$config['Misc']['proxyipheader'] = 'HTTP_X_FORWARDED_FOR';
and remove the two slashes in front (//) - this is called UN-commenting the line. Re-save the file and upload it to your server.
IP addresses will now be taken from the HTTP_X_FORWARDED_FOR header.