@Delphie Take a look at this post. You can give it a go and check how the Eeasymesh would perform for you if there's any improvement.

@Haring The FW version that you've found is for a US region device. Look at your device bottom sticker and check the FW region - details. If your device is with an EU region use this FW release to...

@byrallier AX90 supports Onemesh technology. Here's the difference between different TP-Link mesh technologies. The main goal of a mesh technology would be the seamless roaming between different...

@I-Data How about this guide - I believe that's the guide what you're looking for.

@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: