iMac Wont Connect to Router by WIFI

[Lesleybd]

A couple of months ago I changed to Fibre 150. All my devices are working perfectly except for my iMac. I usually connect it via ethernet but recently tried to connect by wifi. It won't connect. I spent an hour on the phone yesterday with Apple Support and it looks as if the issue is the router. I can connect via a hotspot using my phone and I can connect to a nearby  unsecured network. Mac diagnostics say this: 

Self-Assigned IP Address

Your Mac has a self-assigned IP address because it can’t locate a DHCP server.

A self-assigned IP address is provided by the Mac itself when it cannot find a DHCP server. Your Mac will require a valid IP address before you will be able to connect to the internet.

Contact your Internet Service Provider for further assistance.

Has anyone had a similar issue? I dread phoning support because I know they'll just blame my Mac.

[kanya-TT]

Hey there. @Lesleybd. Please advise if you are still experiencing the same issue.

Kanya

[ferguson]

Ha, the main thing is we got there in the end!  

[ferguson]

Ha, the main thing is we got there in the end!  

[Lesleybd]

It would seem so. 

I once read this, "insanity is doing the same thing over and over and expecting different results” and someone had added “except when you’re working with computers". 

Thank you for your willingness to help with this issue.

Lesley

[ferguson]

No worries, so you've got it sorted now?

[Lesleybd]

Thank you. Got confused between the public page and the private messaging. 🙄

[Lesleybd]

I went into my wifi details  to check we were on the same page  and noticed I now had information in the Ip Address and Subnet Mask fields that had previously been empty. Tried to connect and suddenly I'm connected! 

[ferguson]

Yes. 🙂

[Lesleybd]

I am running the latest version of Sequoia. The Apple support person told me to update as part of her trouble shooting.

Do you mean Keith's post where he told me to choose 'using DCHP' from the wifi TCP/IP settings. ? 

Lesley

[ferguson]

@Lesleybd 

May I just ask, are you running the latest version of macOS, Sequoia 15.6.1? Can you confirm that your Network settings are as shown in @KeithFrench's post, message 25?

[Lesleybd]

Not sure I clicked Send on this screen shot.

EDIT from KeithFrench: Thanks for the image, which I have now removed as this is a public forum.

 

[Lesleybd]

Same screen once In plugged in my ethernet cable.

EDIT from KeithFrench: Thanks for the image, which I have now removed as this is a public forum.

 

[Lesleybd]

Thank you, Keith.

I really appreciate your extensive efforts to resolve this issue.  I have tried the advice in your post above but I'm still not able to connect via wifi.

Thank you for suggesting @ferguson

Regards

Lesley

[Mandisa-TT]

Thank you @KeithFrench

[KeithFrench]

Hi @Lesleybd @Mandisa-TT 

Having analysed the Wireshark traces you provided and inspected the config screenshot from the router's DHCP page, I think this is an issue with your iMac. This is based on you always getting the Self-Assigned IP Address on a connection attempt and all of your other devices connect OK, so the DHCP server in the router must be working OK.

I have just done some Google searches on this error & found this possible solution-

Make a New Location, Using network locations in Mac OS X ...

http://support.apple.com/kb/HT2712

System Preferences>Network, top of window>Locations>Edit Locations, little plus icon, give it a name.

System Preferences>Network, click on the little gear at the bottom next to the + & - icons, (unlock lock first if locked), choose Set Service Order.

The interface that connects to the Internet should be dragged to the top of the list.

Sys Prefs>Network>highlight the Interface you're using>Advanced>TCP/IP>Configure IPv4: Using DHCP.

If using Wifi, instead of joining your Network from the list, click the WiFi icon at the top, and click join other network. Fill in everything as needed.

My fellow Community Star @ferguson has a lot of knowledge where macOS is concerned. If my suggestion above does not work, perhaps he will be able to assist you.

[Mandisa-TT]

Thanks @KeithFrench for assisting.

[KeithFrench]

Hi @Lesleybd 

Thanks for the trace. The first stage of the DHCP process for a device to obtain its IP addressing information is to search for a DHCP server. This is not happening in the trace at all. 

Please can you check first of all that your MAC is configured to get its IP address via DHCP? From a Google search, this is how to do it:-

1. Click the Apple menu in the top-left corner of your screen.
2. Select System Settings from the dropdown menu.
3. Scroll down and click on Network in the sidebar.
4. Click on Wi-Fi in the Network settings.
5. Click the Details button next to your Wi-Fi network.
6. Select the TCP/IP tab from the options at the top.
7. Click the Configure IPv4 pop-up menu.
8. Choose Using DHCP from the list.
9. Click OK and then Apply to save your changes.

Thanks.

[KeithFrench]

No worries @Lesleybd, whenever will be fine.

[Lesleybd]

Thanks, Keith.

I will probably use the Dropbox solution but it might take me a while to find what channel my router is using so it will probably 

be tomorrow before I get back to you.

[KeithFrench]

Can you add a password to the zip?

[ferguson]

@KeithFrench 

On a mac you just need to right click/ctrl-click the file in question and this brings up an action menu which includes a Compress option. Selecting that creates a zip version.