Neatgear wifi extender suddenly becoming slow

Model EX2700 – N300 WiFi Range Extender Essentials Edition

Ive had this for nearly 2 years now it is great gave me a very good signal in my room which never used to have good connection otherwise. Lately ive noticed a drop in signal it is nowhere near as quick as it used to be and sometimes itll disconnect all together so i have to manually reconnect. Looking online it said to update the firmware and reset the extender, i did that but nothing has changed. I contacted support and they said it was to do with my network and that i needed to change something but im not sure how tongo about fixing this on my own if someone could be so nice and help me that would be much appreciated. Any instructions would be helpful as im confident id be able to follow them correctly.
Thankyou:)