Intermittent Log In Problems with MacBook Air.

I generally have good performance from my fibre wifi. However, I am rarely able to get my MacBook Air to connect properly with wifi. I have just replaced a 6 year old MacBook air with a new one and have the same problem. The wifi is showing as being logged in but I am unable to log into any website (message saying 'you are not connected too the internet') and iCloud and Gmail email just shows as 'connecting' on apple email. Sometimes it just takes ages to connect but most often I will need to switch off the wifi on my MacBook and switch it back on again which ultimately clears the problem. It will take multiple toys on occasions. I recycle the router every month or so and this seems to help as well. All other devices connected to wifi (including multiple Apple products) work without a problem. 

It's irritating but not worth the time trying to get hold of someone in Customer Service but I am wondering if anyone else has had the same problem and solved it? A possible conflict that exists on the MacBook Air and nothing else seems likely but I don't know what. Any suggestions would be appreciated. Thank you.