I don't know what firmware version means, I tried downloading firmware but my wifi just throttles every time I do.

I recently got a tp-link for my house, and all is well except for when I try to download anything, or if my phone auto-updates an application, the entire network crashes.

I've tested with/without the TP-Link and this problem only arises when I am on the TP-Link

I don't really know what to do, and people keep overcomplicating everything with all this terminology. Please be simple with me, I don't understand it. It's frustrating being stupid. 

I've searched around for 3/4 hours on these forums and on different websites which all usually lead me to 'http://tplinkmodem.net' - but I am unable to access this website as I am "not connected" despite having an ETHERNET CABLE attached to my laptop. It doesn't make sense. I don't understand it. It's wrong. I don't understand how this is a modem as a powerline cable? i just dont

Please can someone just guide me extremely bluntly as to what i do. I just want to download things. I can't.

Thank you in advance