UPDATE 10/4 6:47 EDT
I have been going through all the comments. THANKS!!! I did not know about the techniques listed, so they are extremely helpful. Sorry for the slow update. As I mentioned below, I got behind with this yesterday so work cut into my evening.
I ran a port scan. The first syntax, -p, brought no joy. The nmap software itself suggested changing to -Pn. That brought an interesting response:
nmap -Pn 1-9999 <Local IP Addr>
Starting Nmap 7.93 ( https://nmap.org ) at 2024-10-04 11:44 BST Failed to resolve “1-9999”. Nmap scan report for <Local IP Address> Host is up (0.070s latency). All 1000 scanned ports on 192.168.0.46 are in ignored states. Not shown: 990 filtered tcp ports (no-response), 10 filtered tcp ports (host-unreach)
Nmap done: 1 IP address (1 host up) scanned in 6.03 seconds
Just to be absolutely sure, I turned off my work computer (the only windows box on my network) and reran the same syntax with the same results.
As I read this, there is definitely something on my network running windows that is not showing up on the DHCP.
Any device can decide to set it’s own IP so that’s not too far fetched. Have any IoT crap like a water softener or colorful lights or speakers or cameras?
I have quite a few smart home devices. But the only “crappy IoT things” is an air purifier that is controlled by phone.
Unfortunately, I bought quite a few T-Link products before the IC revealed that they are dangerous.
It is worth exploring.
Edit TP-Link
Ah I have a TP-link router as well, two actually, and Im not monitoring my home network at all. Your experience makes me think I should!