pfSense

missed step 4 which is hit save and apply again.

Raising urgency of bug, as it seems it does actually prevent toggling other settings on the networking page. Until I fix the config my settings on that page are now locked in place, unless I enable the "ip[v6 over ipv4 tunneling again".

lower urgency now.

I fixed my local config with viconfig.

The setting that got stick is 'ipvnat'

It looked like this in the config

<ipv6nat>1</ipv6nat>

I removed the 1 and its normal again.

So if you follow the steps provided it should get in that stuck state.

On 2.4.5.a.20190111.1435 (stock - factory default), able to reproduce the behavior.

Warning: Illegal string offset 'enable' in /usr/local/www/system_advanced_network.php on line 107 Warning: Illegal string offset 'ipaddr' in /usr/local/www/system_advanced_network.php on line 108

Reproduced the issue on SG-5100:

2.4.4-RELEASE-p2 (amd64)
built on Wed Dec 12 14:40:29 EST 2018
FreeBSD 11.2-RELEASE-p6

and

2.4.5-DEVELOPMENT (amd64)
built on Fri Jan 11 14:35:41 EST 2019
FreeBSD 11.2-RELEASE-p8

PHP Errors:
[16-Jan-2019 17:11:55 Etc/UTC] PHP Warning:  Illegal string offset ‘enable’ in /usr/local/www/system_advanced_network.php on line 107

That's a new error, not the same one. I can't reproduce that here, but I can see how it might happen. Pushed a new fix.

Tried on 2.4.4-p3. I do not observe the issue.

0. set IPv6 on LAN
1. enable "IPv6 over IPv4 Tunneling" and set an ip address in the "ipv4 address of tunnel peer field"
2. save (there is not apply only save)
3. empty the "ipv4 address of tunnel peer field" and disable "IPv6 over IPv4 Tunneling" (empty and disable not vice versa, because if disable is performed, then field disappears)
4. save

Config looks fine:

Enabled

<ipv6nat>
    <enable></enable>
    <ipaddr>192.168.128.240</ipaddr>
</ipv6nat>

Disabled

<ipv6nat></ipv6nat>