R7000 address reservation not working as expected for attached devices

Model R7000 NightHawk router

Firmware V1.0.11.128_10.2.112

Mac Monterey 12.2.1, home Ethernet and WiFi network, ISP Virgin Media cable connection, using Hub 3 as cable modem only.

DHCP is enabled on the Nighthawk router, but not on a couple of other WiFi access points connected via Ethernet.

I had a power cut of about 5 minutes a couple of weeks ago. Some network functions stopped working properly, and I'm only gradually sorting them out.

One persistent issue is that my main computer, a late 2015 iMac 5K Retina 27", has the address 192.168.0.2 reserved in the R7000, and that's what the iMac System Preferences/Network shows as its IP address, using wired Ethernet. Its WiFi is turned off.

But when I look at the Attached Devices list it is showing with IP 192.168.0.116.

Why? As far as I can tell, its own network connections are working properly. Does it matter that the router is showing one IP and the computer thinks it has another one?

Another issue is that an ESXi server is not showing at all on the network, although its Ethernet connection on the router, and the intervening switch, shows a flashng light. It too has a reserved IP address, 192.168.0.100, but there is nothing showing in Attached Devices with that IP address, nor the name of the server on any IP address. 

A Virtual Machine  providing a Plex Media Server running on CentOS on that server is also not showing on the network - it's on the reserved address 192.168.0.31. Again, nothing is showing on that IP in Attached Devices, and the VM name Plexserver is not showing either, on any IP in Attached Devices. 

Any suggestions for fixing the odd IP assignment(s) and missing Attached Devices?

I have already restarted the router and the computer (in that order) more than once, and restarted the ESXi + Plexserver machine - a Dell T110 server.