Wifi not connecting

[DudinBedford]

I have a strange problem. The wifi is not allowing connections. This has been working fine for years and whatever I do, I cant get a successful connection. It's been happening for a week but may have been happening as long as a month ago (was on holiday.)
Hardwired connections are not affected and I have full internet connectivity.
The model used is a 8800NL original version, connected to PlusNet Fibre DSL. As I say working fine for years. No changes made to anything that I am aware of other than explained below.
Suddenly no devices will connect to the wifi. Error messages are Denied access to network connection failed (android phone) Unable to connect to Network (W10 laptop) authentication failure (Amazon Fire 10)
I have rebooted the router
I have set up a new SSID
I have removed security on the wifi connection
I have reset the phone network setting
I have forgotten the network on the laptop and required it.
I have turned wifi off on the 8800, attached another Netgear wifi router and the same thing happens albeit on a completely different wifi connection.
I have reset the 8800 to factory settings
I have replaced the 8800 (today) with an 8800R2 - exactly the same once set up to my DSL out of the box.
I am at a loss as to what to try next!
The wifi light is on - all the four devices (two phone) can see the network under whatever new name I give it but they will not connect.
Any ideas?
I'm going to the pub to calm down.....

Thanks in advance
Dud

I've tried removing all password security and making the network open - same error message "Denied access to the network. Connection failed."
I don't have MAC filtering enabled, which would obviously explain the experience.
Interestingly I get the same error message if I have wifi security enabled and whether I use the correct password or not!

[DudinBedford]

and I can successfully connect to someone else's open wifi on the street with the laptop and my phone so the problem is definitely in my house, either the router (unlikely as I have tried 3 now, the 8800 v1 the v2 and the Netgear), the ISP or something else.
I will have to try moving the router, see if that helps - next weekends task as I work away in the week.

[billion_fan]

and I can successfully connect to someone else's open wifi on the street with the laptop and my phone so the problem is definitely in my house, either the router (unlikely as I have tried 3 now, the 8800 v1 the v2 and the Netgear), the ISP or something else.
I will have to try moving the router, see if that helps - next weekends task as I work away in the week.

There must be something interfering with the wifi, as you have tried three devices different models and brands.

Try changing the wireless channel to see if that helps, try channel 1 or 11.

[DudinBedford]

I understand your logic but unfortunately that makes no difference. I live in a cul de sac at the end of a long road, there are only 6 houses here and I am sitting next to the router. Still can't connect but all the devices connect fine at other locations.