Wifi issue with wifi slowing down and disconnecting

Hello,

I have IMAC 27 inch Mid 2010 with

Macos High Sierra 10.13.2

Since updating my wifi is performing really bad.

It slows down over time and then totally disconnects and I am not able to re-connect to network. I need to re-start computer to get it working again.

My iPad, iPhone and other devices have no issue so the router and network is working OK but something seems to have changed on my IMAC with latest MacOS.

Does anyone have the same and now a workaround?

Best regards

/Joakim