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I recently moved house and have had a new router installed in the house which is working fine for all my devices until recently my MacBook Pro 2013 started to have trouble connecting. Ultimately my whole MacBook Pro started playing up but it turned out this was because I was running unofficial macOS (Big Sur) on my old 2013 model.

I did a fresh install back to Catalina but this Wi-Fi issue still persisted. What's odd though is that it seems to only have trouble connecting to this network. Other networks or hot spotting to my phone works fine so fortunately its not a hardware issue.

Each time I click to connect I'm asked for the password and after I enter this hangs about trying to connect for a bit and then says connection failed and I have to restart the whole process again (to no avail). Interestingly, if I enter the wrong password the same thing happens and It doesn't tell me the password is incorrect.

Something more fundamental is going wrong I think. Does anyone have any thoughts on how I can go about troubleshooting this issue? I have restarted multiple times, and reset the PRAM, NVRAM etc but no changes.

Update:

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  • I'd also try resetting SMC. Have look at How to reset the SMC of your Mac Jul 26 at 1:20
  • Your problem looks a lot like a bad MAC address managment between your router ( which is your network DHCP server ) and your Mac. Could you check that your MAC address isn't changing because this might cause problems to your router? You can check this here:  > System Preferences... > Network, then select Wi-Fi on the left, unlock the paddle, click on Advanced... and select Hardware.
    – dan
    Jul 26 at 11:36
  • @dan Hi there thanks for that. I had just solved the issue by logging in to the ip address of the router and enabling a guest network. For some reason my Mac could connect to this and it looks like this has somehow enabled my router to recognise the Mac address of this computer and so I can connect to the original network too. :)
    – Nick
    Jul 26 at 23:48
  • In this case you are in a kind of hot spot network without the usual protection provided by your router for your internal network. If you are interested to fix this and to solve the original problem which is on MacOS side, feel free to provide: - screen capture of the sub-menu of system preferences I talk previously, - configuration of DHCP on your router ( text only is perfect ).
    – dan
    Jul 27 at 5:33
  • If you provide within your original questions the few details I requested, you could make your question a very helpful for a lot of users trapped in Wi-Fi failing since recent iOS and OS upgrades. ( next line in the next comment: newline is swallowed here ).
    – dan
    Jul 28 at 7:45
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From the clear tests you ran thus far, it is clear you dont have an hardware problem and not any NVRAM issue.

Your problem looks like a specific disagreement on the way your router and your Mac manage the attribution of an IP to your Mac to start communicating ( the protocol used for this address attribution is DHCP ).

You can trouble check this disagreement by looking on the 2 sides of the required agreement.

On the Mac side

Open:

 > System Preferences... > Network

then select Wi-Fi on the left. You might see that your IP address is something like:

169.254.xxx.yyy

where xxx and yyy are numbers included in [0 - 255]. ( See APIPA address ).

Next unlock the paddle, click on Advanced... and select Hardware and check your hardware address. This one should like:

xR:xx:xx:xx:xx:xx

where xR and xx are 2-digit hexadecimal numbers ( in [00 - ff] ). If the R digit is:

2, 6, a or e

this means that your MAC address is a random one which will change at any new connection attempt. And the core of the problem is that this is an abnormal behaviour in a normal network ( this is the normal behaviour of a security tester or a criminal which would like to enter a target network with a stolen MAC address ).

Most routers configured to put on a minimal security won't accept such a rotating MAC address for a uniq machine, simply because this is not normal user behaviour.

But some recent recent versions of iOS ( 14 ) and perhaps undocumented updates of MacOS ( more technical investigation needed here ) are starting to use this MAC address randomization function to protect users privacy in an hot spot Wi-Fi network. But this approach is a total failure and is breaking the normal use of DHCP.

[ This caused a huge worldwide surge in support call to fix Wi-Fi network failing after recent mobile phones or computers OS upgrades. ]

On the router side

Check your router configuration which you can probably access through its router address. You will find this router address within the submenu:

Advanced... > TCP/IP > Router:

and search for the specific DHCP configuration tuning.

[ If you want specific help to further trouble shoot this side of the problem, please provide the brand of your router and a screen capture of this configuration menu. ]

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