I connected a repeater to my router archer c20. Very frequently an issue is happening & this scenario happens after using repeater for 2 to 3 minutes , the repeater got disconnected from the router and stopped showing up and as to make it correct i have to restart repeater several time. I think the real problem is with router, because i observed while using several devices simultaneously the router got disconnected from all the device and after 2-3 seconds it reconnects itself with all the other devices (this scenario also happens once or twice a day). I tried

1. different ip spaces so that they 192.168.0.101 to 192.168.0.149 for router and 192.168.0.162 to 192.168.0.199

2. address reservation for repeater in dhcp client list. ( 192.168.0.148) even i tried changing it .

3. tried installing several firmware update (latest archer v4 181213 update dt 29-1-2019 )

few things to know 

when using my laptop directly with the router no disconnection issue

no problem in my repeater because i have checked it throughly while using alone.

I am currently fed up with problem and cannot find a solution to this problem. Pls help if anybody can ?

I think it could  a algorithm issue with the tp link or may be some kind of problem in router setting. I confirmed it with several friends and they tell me its a issue which is persistent in tp link routers.