During boot, the circle LED quickly 'breathes' blue, followed by the square, and finally the diamond. By default, the black diamond LED slowly 'breathes' blue when everything is normal, and the green circle LED slowly 'breathes' red when there is a software update. At least I saved my configuration before I did this 'upgrade', so it should be relatively simple to restore everything the way it was prior to everything breaking.The SG-3100 pfSense appliance from Netgate has three RGB LEDs on the front. In any case, I got a copy of the old firmware (2.4.5-p1) and now I have to wipe the unit clean and reinstall the entire system. I paid for this Netgate appliance because I wanted a 'set it and forget it' type of box where someone else was making sure that stuff just worked. It could be one of several other issues that have also been reported with the new release. And whatever is wrong with mine is more than just the gateway issue described there, because that workaround described in that bug report did not get mine working again. But IPv6 is still broken as the bugs have not been fixed. Fortunately, I was able to find my USB cable and connect directly to the console, see what was happening, and delete the newest configuration file, which got the system booting again. I then started tinkering with the configuration to try to get it working again, and somehow, it wrote a configuration file to the system with a length of 0 bytes, putting the thing into a state where it would not fully boot. I discovered this when phone apps were taking over a minute to launch, which I traced to the apps trying to connect to servers over IPv6, and eventually giving up and falling back to IPv4 when they discovered that IPv6 was not routing properly. Unfortunately, IPv6 worked for about 2-3 days, then broke. I upgraded my SG-3100 appliance to that new release the same day. On 25 February, they pushed out a new release that supposedly fixed the issues with the one issued just 8 days earlier.

Soon after, there were reports of instability issues, IPv6 connections breaking, and all sorts of problems, resulting in Netgate actually pulling the release. On 17 February, Netgate released pfSense 21.02 for its appliances:

Netgate 3100