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macrumors member
Original poster
Sep 30, 2018

I am new to Apple, I purchased a 2nd hand iMac 27" with an Intel Core i5., running High Sierra 10.13.6. All seems well but I am having some connectivity issues with my wifi. When I first boot the mac connects to my wi-fi using my saved credentials. However if I put the mac to sleep (or it sleeps after inactivity) then I'm unable to re-connect. I get a message:

"The wifi network "xxx" could not be joined" - try moving closer to the wireless router....

I have tried manually re-connecting, removing the wifi and re-creating and re-entering credential but it will not reconnect.

The only solution is to reboot again which connects automatically.

Any ideas? Thanks in advance.


macrumors Penryn
Feb 20, 2009
This may not help, but...

Is the router in the same room as the iMac?
If not, do you have ethernet in the room?

I would try an ethernet connection first, if possible.


macrumors member
Original poster
Sep 30, 2018
Router is downstairs and the MAC is upstairs. I have a PC next to the MAC which connects and keep the connection to the router perfectly fine. I have also tried changing the wi-fi channel but I think this is not the issue, it seems th issue is with the MAC itself.


Staff member
Aug 9, 2009
A sea of green
Run the Wireless Diagnostics app.

When the app first comes up, choose the Monitor or Performance pane, and keep an eye on your RSSI and noise. If they're low, your connection might be marginal. See the heading "Use other diagnostics utilities" at the link.

You might find it useful to log some data, which I think will collect data when your machine wakes from sleep.

Also, are you using the 2.4 GHz or the 5 GHz band? They have different distance and penetration parameters, and one might work better than the other.

If your wifi access point (router?) has both bands, which one is your Mac connecting to? Does the router give them the same name, or is there a distinction like one one has a "5" in it, so you can tell what you're connecting to?

Which router?
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