:confused: what's your model number of the router and the WAN IP address on the router? Which IP address did you ping?

TP-Link smart device does not support hidden Wi-Fi. Do you mean you can't get it connect to a hidden Wi-Fi?

Hey, the hardware version is the same, mine is also V5. Not sure whether it is suitable or not, but you can have a try. http://support.tp-link.com/f/e632871d5a/?dl=1 If there is any error, do not...

try to change another wireless channel on the main router and reboot the bridge router. Besides, make sure both of routers have the latest firmware.

Is it the latest firmware? Is there any spliter? try to remove spliter and connect telephone line to the modem directly. If the connection still often drops, it's recommended to email tp-link support...

You mean the connection in the office often drops? However, the connection at home is still working properly? If the home connection works properly, you can try to reduce the clients in the office....