Hi@Fleczer,

If you are experiencing intermittent wireless connection on the range extender, please refer to the following suggestions:
1. Confirm the extender is properly located based on How to Upgrade the Firmware on the TP-Link Wi-Fi Routers?
2. Make sure the firmware on the extender is up-to-date.
3. Enable “High Speed” mode if you have a dual-band extender.
4. Disable Parental Control or Access Control (Blacklist/ Whitelist) on the host router if they have been enabled for the extender.
5. Turn off Band Steering (also called "Smart Connect" or "Whole-Home Wi-Fi") and set up different Wireless names for the router's 2.4Ghz and 5Ghz Wi-Fi.
6. Fix the wireless channels on the host router, such as channel 11 for 2.4GHz and channel 48 for 5GHz.
For more details, please refer to https://community.tp-link.com/en/home/forum/topic/272398.

  @Joseph-TP thank you for your reply.

1. This is ok, as I stated - range of the main router is good enough to work even farther from the range extender with stable connection

2. It is up to date on both the router and range extender

3. Could you tell me how do I set this up?

4. I don't use either Parental Control or Access Control

5 and 6 DONE

But I still have this issue.

Is there any setup that cuts off the Internet on range extender when it is used with heavier load? The issue appears mostly when I and my wife are connected to 5G via range extender at the same time. But if one of us is closer to the main router, the issue does not appear.

Quality of Internet is not a problem since I have 1GB via optical fiber and it is always stable on the main router.

Hi  @Fleczer,

Which wireless signal lights on the range extender are off each time the problem occurs? 2.4Ghz or 5Ghz or both?

The location where you currently place the range extender is a bit far from the router. Please place it closer to the router for comparison.

In addition, please log in to the web interface of the range extender, go to settings->Network->Tap Router icon, check the negotiation rate of each frequency band here, and provide a screenshot. This will help us locate the problem.