Wifi Connection Slow, and speeds up when I reconnect

Hey everyone

I have a strange issue with my wifi router. Its generally pretty slow at the best of times (I live in AU, the internet is terrible compared with NZ), and often it will slow to a crawl. To fix this I have found that reconnecting to the router by turining airplane mode off/on will speed up the connection.

This happens on iOS and on Win10. What is causing this and how can I fix it?

Cheers

Steve