@jupiter If you are seeing like this 👇🏻 because you are trying to access over https and Deco Web UI does'nt support https so you have to access Web UI without https like this http://tplinkdeco.net...

@Spike1 You can download from the link which is David provided to you.

@David-TP Thanks for your answer.

@David-TP My friend bought Deco M4 (V2.6) US version so can he able to install (V2) firmware file into (V2.6)

@NathanF1 Actually your PC is connected through Deco S4 and Deco S4 is not supported Speed Limit function that's why the function is not working properly. You can connect PC directly to Deco X55 if...

@meemee You can change DNS Server to Google DNS 8.8.8.8 and 8.8.4.4 in the Internet Connection option and DHCP Server.