5Ghz wi-fi stopped working

[ashleykaryl]

Last night I found this thread and it looks like there were problems during the beta stages of Sonoma and indeed with Ventura that remain unsolved.

https://www.reddit.com/r/MacOSBeta/comments/1420udk
https://www.meter.com/mac-osx-awdl-psa

 

[ashleykaryl]

@modisto I may have found a fix here, at least it's working so far.

In your router change the DNS to use Cloudflare. If you have a separate modem change it there as well. This DNS blocks malware.

Malware Blocking
Primary DNS: 1.1.1.2
Secondary DNS: 1.0.0.2

Now wait a minute or two and try a speed test. I am suddenly back to my old faster speeds over 5Ghz.

I also wonder if this might be related in some way to specific routers and security settings.

 

[ashleykaryl]

Two days have now passed since I changed the DNS on the modem & router and my 5Ghz wi-fi is still good. I guess the big question is what Apple has done that is causing some to see these big slowdowns and what is happening with that Cloudflare DNS that is mitigating against the problem. I wouldn't exclude this being down to specific routers and security settings either, but this appears to have fixed it for me and it is consistently better than the power lines that I purchased.

 

[ashleykaryl]

Just a follow up on this in case others experience similar issues. After changing the DNS in the modem and router I had fast 5Ghz speeds for three days, until I shut down the computer. When I started it again it was slow, so I put back the power lines and they seem to work well, as long as we don't turn on the dishwasher or oven in the kitchen, which shaves off roughly 40% of the download speed.

Seeing that the DNS seems to be at play here in messing with wi-fi speeds I just flushed the DNS in the terminal and that fixed the 5 Ghz wi-fi speeds again.

In the terminal type:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

Then add your password and hit the return key to flush the DNS cache and see if that works. For me this all points to a bug in Sonoma and having to work around it until Apple issues a fix, but I have a far better understanding now than I did a week ago.