Ex3700 Constant Internet disconnects/connects!

Hello.

I have had a WiFi Range Extender since September due to having almost 0 coverage in my room (I can infact get internet if I'm on one side of my bedroom, but it's quite slow). I currently have a Virgin Media Super Hub 3 in my living room.

I bought the NETGEAR EX3700-100UKS AC750. I set this up very quickly and very easily. I had no issues at first, but then I noticed that I kept getting kicked/disconnected from online games on my Xbox One. I could rejoin 1-2 minutes later, but the damage was done (team losing, my account punished for leaving early etc). I spoke with Netgear support about this, but we did not come to a solution and they suggested moving the WiFi Range Extender and so I did.

I now have 70 Mbps (compared to 50 before moving it) down from a potential 200 (all speed test results). This is fine, providing I get a constant internet connection.. But I don't. 

The issues with getting disconnected have continued and dare I say become worse. I no longer use my Xbox in my room, because I cannot play online without getting disconnect (and then punished due to the nature of the games, punishing players who leave early). I do still use my laptop, but I am constantly sat there waiting for connection to return. 

I've been living with the problem for a while, so it is manageable, but it's extremely annoying due to having over an hour of usage online I am only actually able to load pages for about 40 minutes of that time. 

I have Skype running this moment, and whilst typing this message I have been disconnected twice (noticed due to the symbol changing to offline and back to online) for around 1-2minutes both times. 

It's worth saying that the internet connection remains the entire time, pages just do not load during this period. 

I am clueless to what the issue could be, if there is anything I need to post to help diagnostics please let me know. I hope someone in this community can help me!

Thank you.