A few weeks ago, I finally got around to enabling IPv6 support on my network. I’m using Hurricane Electric tunnel broker (as my small ISP doesn’t support IPv6 or have plans to 
). I’m happy I got IPv6 working, and I don’t want to disable it, but it does have some drawbacks. Most notably, pfBlocker has only a handful of IPv6 dns-blocker and ip-blocker feeds. As a side note, I’m using the pfBlocker-devel version since the standard version’s GeoIP blocking capability randomly stopped working. In addition to the limited number of pre-compiled feeds, DNS lookups for IPv6 addresses is spotty at best. So known websites that I whitelist or blacklist, can end up slipping through IPv6 rules, with no real means for me to identify where the IP is coming from.
All that explanation was simply to illustrate why I need the pfSense “Prefer IPv4 over IPv6” feature. I only want to use IPv6 if IPv4 is not available, or some other edge case that would require it. Before setting up my IPv6 solution, I tested the option without any issues. Now, it seems, applying the setting causes a crash ,not a whole system crash, it does recover, but nonetheless the setting never gets applied. The error reported is:
[19-Jan-2019 00:07:42 America/New_York] PHP Fatal error:
Uncaught Error: Cannot unset string offsets in /usr/local/www/system_advanced_network.php:112
Stack trace:
#0 {main}
thrown in /usr/local/www/system_advanced_network.php on line 112