I keep having strange things happening on my iMacs wifi. I went over to fibre and my speed should be 40mg & 9mg and get this for a while until it drops to 8 & 7 ? Now I've googled it and messed around with with mac settings with no joy. Ive opened up the router and changed channels and sometimes the speed increases to what it should be but eventually drops back to the slower speed and stays there until i mess with the channels again. Any ideas anyone ?