I am using a TL-R600VPN router connected to a fibre ONT to access the internet and on the other side, I have 5 deco M9 Plus. The problem started a couple of weeks ago and to be exact it started after my iOS 15.0.1 update which is just a coincidence.

My iPhone started to switch between mobile data and wifi every minute or less than that. Initially, I thought that the problem might be with my iPhone's wifi module and sent it for repair and I was told that when the service centre tested the phone for about 3 hours plus it did not switch out of the wifi. So the service centre asked me to check my networking. I was running the 1.6 beta (not exactly 1.6 beta but something in between the original 1.5.1 and 1.6 which was recommended by TP-link) on my M9 Plus. So thought it might be giving a problem and then reset it back to 1.5.1 which is the stable release. The problem still remains but all my other devices including two iPhones, 2 surface pros and one Asus laptop and about 40 over wifi switches at home, all are connected without being disconnected. Then I checked the log of the R600VPN router and I found that the router was updating the IP addresses of the devices on the network every minute or so. The lease time set is 120 minutes. I have reset my iPhone, today have reset all my 5 Deco M9 Plus and yet the problem remains.

I plan to factory reset the router. That's the only device I have not reset yet. I plan to back up the settings and then restore the settings.

I would like to have some help regarding my issue:

1. What likely is the issue?

2. When I restore the setting from the .bin file, will all my settings including address allocation, time based blocking, ISP password be restored or just certain sections only?

3. Can this issue be solved without resetting the router?

Any help is appreciated.