TP-Link TL-WR802N cannot connect as a client

[#1]

I have been trying to connect TP-Link TL-WR802N to my PLUSNET router.  I have tried several things and asked the company TP-LINK for their help.  I followed their instruction http://tplinkwifi.net/ to connect to an oil tank -  https://lincs.myolive.co.uk/ This unit keeps an eye on my heating oil with usage and more details so as we don't run out of oil.  The problem started when we had another internet system 4G EE internet.  I now want this TL-WR802N to work on my PLUSNET router.  And nothing seems to work.  I cannot find the Router's IP address http://192.168.0.1 or http://192.168.1.1 at all.  Just says no service.  The OLIVE has to be connected to this via a ethernet cable to the TP-LINK.  Then that TP-LINK is set on wireless client.  Nothing seems to be working:

1. Ensure that your device has connected to the router only.

2. Open a web browser and enter 192.168.0.1 or tplinkwifi.net in the address bar and give it a go.

3. Otherwise, please check the default gateway of your device and use it to access the internet: https://www.tp-link.com/en/faq-838.html

4. Meanwhile, you can use different web browser and devices to access.

5. Besides, you can try to reset the router and login with the default username and password.

Here is an instruction you can refer to: https://www.tp-link.com/en/faq-2236.html 

The other option is to connect the olive system to the PLUSNET router?  But there is a problem in that it needs power via a USB port.  Anyone out there needs a challenge?  Cuz I iz *issed off

[#2]

So what is this olive thing? Does it need a separate power input via USB and wireless for the oil level? If so why not just use a standard USB power supply, such as a phone charger for power and use the Plusnet router for the wireless?

[#3]

Does it have to get power via USB?

There's always Power over ethernet - bit costly for initial setup though.

[#4]

If you are looking for a cheap and reliable PoE solution I would recommend this, I use one to power my GrandStream GXP2140

[#5]

My reading of the very sketchy data that I have found on this olive monitor is that there's a sensor on the tank which is connected to a USB powered wireless transmitter, which in turn connects to the router over a wireless link

Consequently PoE is not required.

[#6]

If you do a Wireless scan do you see anything like this Olive actively broadcasting, as like a Wifi Access Point would be?