I'd grab a WiFi analyzer to see how many routers were on my channel and move the channel as needed. Use the 5GHz range if you can - less subject to interference. Get a new WiFi adapter for $15, link below. That laptop is a bit old so a USB WiFi newer adapter is a cheap fix. You didn't mention if it's Win 10 but there were some issues recently so check your updates.

Here's a link to free WiFi utilities that will help

https://www.nirsoft.net/

Example USB Wifi adapter

https://www.amazon.com/TP-Link-wireless-network-Adapter-SoftAP/dp/B008IFXQFU/ref=sr_1_3

I just saw your comment, thanks!, and was researching other symptoms that I discovered 2 days ago.

I can no longer connect to the Internet from the laptop (Windows 10) but still see networks listed on the laptop when I ask it to show all networks.

When I go into 'Manage known networks', only one of my two networks will display (I also see other neighbor's networks) but my tablet works fine and displays both of my networks. I have moved the laptop to other locations in the house but no change. My network listed is set to 'connect automatically when in range'. Airplane Mode is off. Oddly, the base of the laptop has a light with a WiFi symbol that is currently lit orange. The online documentation on the PC does not say what the orange light means.

Q. so how do I check my W10 updates? Ever since Windows upgraded from W7, I have no idea where things are any more. ;o(

Q. what is a wifi analyzer? and what is a wifi adapter? what does one do with them? take them to a PC Service Shop to take the laptop's old analyzer and adapter and install the new ones on the laptop?

Q. what am I looking for... in the utilities link? I looked in the network tools (I assume that is what you were suggesting).

Thanks

1) Reboot the router and the laptop.

2) Right click on the network icon in the tray and Troubleshoot Problems.

No luck?

3) Try this site to see if a proxy got installed usually by some malware.

http://www.whatismyproxy.com/

If you do see a proxy grab Malwarebytes (free trial) and run it. If not, next step..

https://www.malwarebytes.com/

4) Uninstall WiFi adapter in Device Manager (right-click on Start, Network Adapter then right-click) and reboot (will auto-install wireless adapter again)

Let me know what you learn

Analyzer info...

Grab "wifiinfoview.exe" from :

https://www.nirsoft.net/utils/wireless_network_view.html

Do you only still see the only one of your two networks? Still no Internet?

What I meant by Analyzer is answered here - if there's too many WiFi routers on the same channel performance suffers. You can see the channels that are being used in this app. This is for later - your laptop cannot connect at all. You would change the channel on your router.

Considering the laptop is 8 years or so old I'd still invest that money in a USB adapter - get the dual band for $18.

Ignore the W10 updates for now.

Rebooting the router itself helped; I saw one of the two networks (probably the 5GHz instead of the 2.4GHz), was able to connect to it and use the Internet. Other info: I had already rebooted the various computers and tablets; the laptop shows all W10 updates done as of the 7th of April and, at least the last few, were successful; I had already run Avira (no issues), MalwareBytes (no issues) and SuperAntiSpyware (minor issue).

I guess I will leave it there. Thanks a lot! Now to work on a W7 laptop that I have ignored for ages. I am sure the habit of touching the screen on that laptop will make me panic until I realize I need to use the mouse. Hee, hee, hee. :o))

Remember, just because a device shows that WiFi is available, just means that it's communicating with your router, not that the router is on the internet. It will see any local networks, such as a wifi printer, etc.