Model : TP Link AV500

Hardware Version :

Firmware Version :

ISP : Netherlands Ziggo

Hi,

My apologies in advance as I'm not very technical with these matters, so please bear with me.

I purchased a TP Link AV 500 extender as the walls between the router and the back of the house are very thick. The extender works ok in terms of receiving a signal but it constantly loses connection to the internet.
The way I get it back is to go to System Preferences on my Mac, Network > Wifi Connection > Assist Me > Diagnostics (at which point it shows that Wifi, Settings, Network settings and ISP are on green) but Internet and Server are yellow - indicating a problem. I then click on the network Link Name (TCP Link Home) > Continue > Choose Wi-Fi under Port configuration > Choose network TP_LINK_BC8FDC > Continue > Network Diagnostics wants to access key TP_Link_BC8FDC in your keychain > Click Always Allow > Quit and comes back up.
5 minutes later and it's gone again.

Just to give you an idea how often it drops, by the time I finished writing this email it had dropped twice already!

Can anyone help please?

Thanks in advance.

Edit: How do I find the Hardware and Software versions?