Hello all, 

I've bought extender RE305 from TP-Link. I am trying to set up the repeater correctly, but for some reason it does not want to connect to 5 GHz network of my main router. It connects to 2,4 GHz without problems. This seems to be same problem as here: https://community.tp-link.com/en/home/forum/topic/166856 (as Ziggo is another name of UnityMedia).

Yesterday, I've noticed that for a few minutes, the LED for 5 GHz was on and that repeater managed to connect for a short amount of time, but then once again it disconnected and now 5GHz connection is once again marked as "out of signal".

My laptop, with Intel WiFi, is connecting normally to that network and connection is working and stable.

My main router is from UPC (UnityMedia), its a ConnectBox standard router.

Some info regarding its firmware:

Standard specification compliant  :  DOCSIS 3.0
Hardware version  :  5.01
Software version  :  CH7465LG-NCIP-6.12.18.25-2p6-NOSH

Currently, 5GHz Wi-Fi is configured like that:

I tried to change channels, even set them to Automatic or even disable 2,4 GHz at all, but nothing helps.

What is seen by TP-Link:

What can I do to fix that issue?