Why does wifi fail when a repeater is connected to it?

Question

WiFi

There is an adsl modem in the house, since the house is three-story, the network worked poorly on the third floor, for this reason I bought two small repeaters and connected them, the network started to work, then stopped working altogether, I thought that the repeaters were weak, and I already bought a router ( xiaomi mi router 4a giga edition), connected it via lan cable to the adsl modem, now the internet works fine, but it happens that the network drops stupidly, here I am watching YouTube, and suddenly it says "no connection", I reconnect, and it works fine again, this happens both when connecting to the network of the repeater and when connecting to the network of the modem. I called the provider, they replaced the modem with a new one, but the problem remained. What could be the problem? And should the adsl modem even distribute the Internet if a router is directly connected to it?

PS: Removing the modem and connecting a router is not an option, because the provider has a telephone connection, and the router needs an ethernet connection.

Answer 1

First, repeaters STRONGLY reduce network throughput.
Every time the repeater needs to receive a packet from the device to the Internet, it must first accept it to itself, and then transmit it to the main router via the same wi-fi channel. Needless to say, what delays arise in this case.
Your adsl modem most likely works in router mode and the poor thing can not cope with the load. I would switch it to bridge mode and raise the connection on the router, but there is a problem

xiaomi mi router 4a giga edition

these chinese routers are usually gomno doggy style. Buy mikrotik and connect it to an adsl router that is configured in bridge mode. The most reliable option.

Answer 2

First of all, you need to find out where the problems are:

1. on WiFi connection
   
2. on the LAN connection of the router with the modem
   
3. on an ADSL connection with an ISP
   
4. somewhere further
   

Run four pings and see which ones bounce.
To find out what to ping - run a trace.