If you haven’t done so already you may want to see the various discussions in the OS5 EX Series subforum (where there is discussion about the OS5 EX2 Ultra) about Big Sur issues to see if there are any solutions to your issue.
After some online research, I learnt enough that an “arp -a” command in terminal will list all my attached derives, and that 192.168.1.116 is the IP of my drive (it even knows what it is).
When attempting to connect to it vis browser or cmd-k in the finder, I get nowhere.
Now that “Network Utility” is replaced by using terminal, I have no idea how to attempt to ping the device as my knowledge of UNIX is too small (but I suspect Pinging it would work).
After some time on the linked forums, I don’t think I found an answer to my question (or if I did, it wasn’t written in way I recognised).