agree with Danymarc. TL-WA7510N is a 5GHz product and you can't search it if your wireless adapter don't support 5GHz.

yes, the channel should be the same with your main router as security type.

Can you access internet from your wireless router directly? Doubt you haven't configure range extender successfully.

Perhaps your driver hasn't been installed successfully. Go to the link to download the driver: http://www.tp-link.com/en/support/download/?model=TL-WN727N&version=V3#tbl_a Then, please refer to the...

It seems that you haven't set up range extender successfully because it needs same security information with your BT router. Refer to the following link to configure range extender:...

Even the wired client direct to the BT Homehub is the same. If you unplug TL-WA701ND and try it again with your BT Homehub, can you get normal throughput like before? Are there much wireless...