First LUKS must be open, only then it gives access to the filesystem, and encryption will always add an extra complexity layer, I recommend only using it if really needed.
It's difficult to say, if you have any spares of that, like a different PSU start with what you can test and rule out, you can also try with just two DIMMs at one time, to completely rule out the RAM.
I'm really not a network guy, but always read you need different subnets for that, you can also add the server name with the 10GbE IP to the hosts file on the client computer, so you can access it by name still using 10GbE, that's what I do.
If the disk was empty might as well reformat, but you can try to mount it with UD plugin and if it doesn't post the diags (key needs to be the same as other encrypted disks in the server).
Does is still reboot frequently with the RAM running @ 2133 MT/s? If yes one thing you can try it to boot the server in safe mode with all docker/VMs disable, let it run as a basic NAS for a while, if it still crashes it's likely a hardware problem, if it doesn't start turning on the other services one by one.
No valid filesystem is being detected, so there's serious damage to the superblock which may make recovery difficult, all your other disks are empty, was that the only disk with data?