WiFi "Interferrence" / "Instability" Solution

[Orlando1]

My home WiFi has suddenly "become unstable" after working without significant issue for some time. This is not the routine type of issue I have found answers to on the Internet. It seems that recently when two certain PC's are being used that they interfere with each other causing both to be unable to connect to the WiFi. This was not a problem before and there are other PC's and smart phones that are still using the same router without a problem, even concurrently. It appears that just these two PC have the issue when they are both operational. The connection seems to "bounce" (trying to reconnect, does then fails and tries again). Even if I connect my PC with a cable into the router it seems to oscillate between Ethernet cable connection and wireless connection. When one of these two "troublesome" PC's is switched of the other can function again while the rest of the PC's / smartphones are not affected in anyway. If anyone has clues as to the root problem you will end a very frustrating period with the use of technology.

 

[Orlando1]

I am happy to report that the problem went away by itself - quite mysteriously in a similar way to how it arrived.

I started reading up on WiFi and everything related to it to better understand the technologies involved.
One can rapidly get into the depths of the basics and lost in a short space of time - although the education was useful.
I learnt a lot but did not (consciously) change anything in the WLAN or user devices - and then suddenly both PC's could connect.
Simultaneously again and without interfering with each other!

The one Apple Mac user using the WLAN did report less reliable connection after this improvement of the PC's connection.
But this user did not experience failure to connect or a "bouncing" connection like the PC's did.
I did not investigate it but mention it as it may be a clue to some other better informed user reading this.
Perhaps there is some conflict caused by different operating systems, although other PC and smart phones have never had a problem.

Since then the problem has returned briefly, again for some unknown reason.
We resorted to successfully using Ethernet connections for a day or so.
During this period the router did need to be rebooted once.
Besides this action taken, no changes were made and the problem went away.
Since then we have not experienced the same problem again.
All the devices are operational without any issues once more.