Thanks I already found the IP address, and it allowed me to log in and update the firmware, but when I tried to change the password it gave me all sorts of grief (basically wouldn’t recognize the old password or allow me to input a new one). And I still can’t find where to change the wifi password.
If I were at work, I’d assume you don’t have the right password for one reason or another, reset the darn thing (there will be a tiny switch somewhere, find the manual online) and change the passwords.
You should wait for MD to come back.
Login to the router and it should tell you the type.
Google your model, and “manual” and you should find something like ftp://downloads.netgear.com/files/wgm124_setup_manual.pdf
This model (from 2004!! ) see page 4-5 be sure wireless security is enabled, set to WPA-PSK, and select a hard to guess passphrase.
If your wireless asks for a password, then it definitely has WEP or WPA/WPA2 security. If it’s a word, then WPA/WPA2. I can only conclude the neighbours somehow acquired your password. sAs you say, it never forgets, so either they guessed it, they had a friend do their hacking, or at one time someone who knew the password typed it in for them. If they are not tech-savvy and don’t have their own wi-fi (I assume they have internet?) they may not realize they are using the wrong internet.
(IIRC - tech alert - if they do not know the password, they would not get an address or communicate on your network.
They would show up under “connect to a network” in the Control Panel, Network status and Tasks, connect to a Network.
If the show up in Computer - Network (in the right-hand panel) under “Computers” they are on your network.
Open a DOS/CMD box, ping their network name
PING JOES-PC
Then type the command
ARP -A
find the MAC (ethernet physical hardware) address for the IP address, similar to
Interface: 192.168.0.101 — 0xb
Internet Address Physical Address Type
192.168.0.1 1c-af-f7-d6-91-d2 dynamic
192.168.0.100 00-25-4b-b4-3c-ca dynamic
192.168.0.103 00-0c-29-b0-f7-f3 dynamic
They are using your router, they get an address from the router through “DHCP” request.
Most routers have the option of blocking these MAC addresses. Note their MAC address, block it according to your router’s instructions.
Yes, I checked the router earlier it’s definitely WPA-2 Personal. I also was finally able to locate the model information (after I logged onto it). Likely my daughter used their computer and connected to my internet and forgot, and they probably just don’t realize they’re on the internet on my wireless rather than theirs. I just pinged their computer and the request timed out. Does that mean anything significant? 
I really really appreciate your helping out.
If you pinged and it timed out, they are not currently active/connected to your network. I don’t know how long the entry sits around in “Networks” so it’s possible it’s been there a long time and they have disconnected (or daughter did so when she was done). Just ping their PC from time to time and see if it ever comes back online If not, you’re fine.
Also check your router’s (DHCP) address leases from time to time. Usually, these have a lease time of between 1 and 8 days, so if you see the lease there, they’ve been on in the last X days. If they never seem to be on, assume it’s a leftover from an much earlier connection.
If you are really worried, change your wifi password, and update all your equipment to the new password. That’ll make it official that they cannot get on.
Thanks, will do.