An alternative way to do this without changing the static IP address on your UnRaid server is to go into your eero app, go to "Settings", "Network Settings", "DHCP & NAT", and click on "Manual IP". You can then do the following:
-Ensure that your "IP address prefix" matches that of your old server (example: if your previous router's IP was 192.168.1.1, you should use the "192.168.0.0" default prefix for this eero setting).
-Set the "Subnet IP" to that which was on your previous router (example: if your previous router's IP was 192.168.1.1, the "Subnet IP" in this eero field would be 192.168.1.0)
-Set the "Subnet Mask" to 255.255.255.0 (the eero app default will likely be 255.255.0.0, but don't use it or you won't be able to save the eero app's manual IP configuration)
-Set the "Starting IP" to that which your old router started with, PLUS a number which is more than the total of number eero devices that you plan to use (router and satellites). This is because the eero devices will automatically be given IP addresses starting with xxx.xxx.x.1 - and increase from there. (ex: if you plan to use 5 eero devices, you should set this "Starting IP" value ABOVE xxx.xxx.x.5 - I would set it higher than that in case you want to add more eero devices later. To be on the safe side, I would start at xxx.xxx.x.20, or in this case, 192.168.1.20).
-Set the "Ending IP" value to the same number as your previous router ended with (example: xxx.xxx.x.254 or in this case, 192.168.1.254)
-Click "Save", then "Reboot" when prompted - and wait several minutes.
After this, you will see that you will be able to locate your UnRaid server by typing its old static IP address into your web browser.
BTW, after being in the chaotically inconsistent and problematic Netgear Orbi world for many years, I have found the eero environment much, much more user-friendly and reliable. The eero Pro 6e night is still very young, though ...