@ryg i think u can install the Bangladesh beta firmware first which is so old 2022 or 2023 firmware then your M4 will provide you 5 GHz WiFi connection and then you can install the 1.6.5 stable...

@Marvin_S Don't u see that i set 45 Mbps and im still getting 50+ Mbps

@ryg You can use the Deco M4 as a (Main) unit and then try to install it

@ryg My all Deco M4 units are using 1.7.0 beta firmware i do the same steps which i guided you but i don't know why not working for you 😭😭

@ryg I have guided you all the steps before the TP-LINK engineers but unfortunately all the steps did'nt work 😭 But i think you can try 192.168.68.1 or tplinkdeco.net to install the beta firmware...

@ryg Can you show me your Deco M4 ip address in Deco App because i think you are typing the wrong ip address