@Kevin_Z 

Hello,

So the current issue is that the wireless connection will lose the internet, and you need reboot the router to make it work, while the wired device still works well, right? 

Yes.  As mentioned both iPhone and laptop (home office) are having issues with the internet.  Also a WiFi connected air quality monitor once every 1-2 days notifies was not able to upload for 10-20 minutes.  While wired TV was still able to stream Netflix.

You still can see the wireless network name but failed to connect to them with the error message, is there any error message?  

Yes and no.  Most of the times I could still see the SSID but no error message as far as I know.  Sometimes SSID disappeared.  It may have happened all the times but I didn't check.  FaceTime simply notifies of "poor connection" and laptop stops loading items from the internet.  As shown in my opening message TP-LINK log doesn't show any error.  Any way to obtain a full log from WR702N?

Try a mobile app to analyze the WiFi around you, review all the wireless channels. Next, review the wireless channels on the router. If the channels match that around you, an indication of overcrowded. Manually adjust the channels to lesser use channels.

Not clear.  My Mac lists 16 additional SSIDs other than my own.  It's a tall building.  Isn't clear what else should I do on router to "review and adjust" channles.  Please advise.

There are possibly other wireless parameters that need tweaking, such as Power Transmit, narrow or wide band, etc. but start with the above and below link:

https://community.tp-link.com/en/home/forum/topic/200588​​​​​​

I checked against all steps mentioned in the liked forum message.  We have on average of five devices connected to WiFi and problems began to emerge only about six months ago.

@Kevin_Z 

Hello,

You may download a software called wifi analyzer to review all the channels around you, then try to change to a less-crowded channel on the router to give it a go

I have only Apple devices: any other option?

Also I understand your concern is channel interference from nighbourhood's routers.  But less than once a day and mostly while on FaceTime?

Regards.

@Kevin_Z 

Hello,

forgot the Mac has bult-in Wireless Diagnostics with WiFi scanner.  I am the lone user of a channel.