Issues connecting to internet from iMac

Question

Issues connecting to internet from iMac

This is doing my head in!

Existing iMac -

Mid 2011 running High Sierra. Needed to update to be able to stay current on OS, so purchased -

New iMac

Retina 4K, 21.5-inch, Late 2015, running Catalina. Should be good for a few years yet, right?

Problem

I used migration assistance to set up the new iMac from the old over a network cable. All went fine, and concluded. A few error messages about obscure stuff.

Home Wifi running off a central router. Many, many devices running off the back of its Wifi, including the Macbook on which I'm writing this, the old iMac which is accessing internet just fine, the family TV currently streaming from Netflix, all the family mobile phones, tablets etc. You get the idea - the router is working fine.

But, the new iMac will not access the internet via a browser, either Chrome or Safari. It reports perfect connections using the main router on 2.4g and 5g. I've also connected via my iphone personal hotspot - same result.

But, browsers still report no internet.

So, I hit Google with the problem, and started down the path of working out what's wrong. One of the first steps, of course is to confirm your OS is fully up to date. So, I went down the route of updating to Catalina 10.15.6, which worked flawlessly !!! So, the Wifi connection is in place, and works, but it's just the browsers that can't access anything.

I've tried the various suggestions such as setting up a new Wifi location, which seems to be the silver bullet for some, however the IP address already allocated was fine, and perfectly logical for the router's DHCP table, so this made no difference and didn't work.

I'm really at the end of my tether here. Any ideas as to what I can try next ?

Thanks

Posted on Jul 26, 2020 11:07 AM

Reply

Answer 1

BDAqua

Level 10

245,393 points

Jul 26, 2020 5:32 PM in response to SilstonGeezer

Hello,

Are you running any VPN, Anti-Virus, or Cleaning apps?

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.

System Preferences>Network>choose interface>Advanced>Proxies Tab, make sure none are set, like for HTTP & HTTPS.

System Preferences>Network, unlock the lock if need be, highlight the Interface you use to connect to Internet, click on the advanced button, click on the DNS tab, click on the little plus icon, then add these numbers...

8.8.8.8

8.8.4.4

1.1.1.1

9.9.9.9

Apply.

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Answer 2

Jul 27, 2020 5:50 AM in response to BDAqua

Thank you very much BDAqua for your detailed suggestions.

I was able to do everything you suggest above, however none of the steps solved the problem. I have the older iMac, running High Sierra beside the replacement iMac, running Catalina, and along with enacting all your suggestions, I checked the equivalent setting etc on the older iMac that's still working fine, and everything is the same!

Which left me with the final suggestion, to replace or add the DNS entries, and there I hit a problem. On both iMacs (and indeed on my Macbook), the only DNS entry is the root IP address of the router (Huawei B525 - 192.168.8.1), but that's providing a good internet service on the one iMac and the Macbook. On all machines it's greyed out, confirming it's allocated by the DHCP on the router. I also logged all 3 machines on to my iphone hotspot Wifi connection. The IP address was different of course, but otherwise the behaviour was precisely the same.

However, on the older iMac, and my Macbook, I was able to replace the allocated address with the addresses suggested by you, but on the problematic machine, on clicking the + the greyed out address disappeared momentarily, with a black 0.0.0.0 ready to accept my input, but within 2 seconds disappeared to be replaced by the original, greyed out address. This repeated on every attempt. It's clearly something going on with that one iMac, preventing any editing of the DNS addresses.

I'm going to try wiping the disk and doing a clean install of the OS. I'll post back the results.

Thanks

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Answer 3

Aug 9, 2020 3:48 AM in response to BDAqua

Hello

Sorry not to have posted back before. My attempts to boot in safe mode where unsuccessful. For some reason the "chime" wasn't happening, and I'm using a bluetooth keyboard, so even though I tried holding the shift key in different permutations, I never got it into safe mode.

I did get a USB stick with the High Sierra installer on it, and that installed fine on a newly wiped SSD drive. I then upgraded the OS to Catalina, and everything was fine and working OK, and still is.

So, I'll never know what it was causing the issue.

Thanks for your help though.

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