@I-Data This seems to be a universal configuration guide - there's no device models pointed explicitly like in this example: Do you have any issue sfollowing the guide ?

@Louis_A Can you post the AX5400 Nework Map screenshot here:

@Nemoadest Good job. Refer this thread for MR600.

@JustMeThree On the device bottom sticker is printed the exact router model, FW region and its HW version - details. Can you post this info here ?

@ZeshanAuto OK, Now it's clearer. You mentioned that C20 is using 5GHz to connect to your main router - correct ? Have you try to configure the 2.4GHz band to connect to your main router and check if...

@maxmonz Indeed the latest FW release. I found a similar problem in the Netgear community though. Have a look and see how this was resolved. If that doesn't work for you can try the AX55 Pro in AP...