Yesterday my Mac started working really wonky. In fact, both of them did. It wouldn't load YouTube up at first. Finally, it did but not all the pics would load up. When I finally loaded up a video it kept buffering. I tried using my alternate log in, using it in Safe Mode, used Disk Utility, used Malwarebytes in case I had malware, restarted the router and modem, and restarted my mac. Nothing worked. I couldn't even get the Ookla speed test to work. I did a network diagnostic test (clicked on option + wi-fi icon) and it said it was fine. It wasn't.

Today I had the same problems so I did another Network diagnostic test. It showed errors that I wanted to send to you via Imgur but Imgur said my .png screen shots were not allowed! What? I screen shot Imgur itself and it accepted it. Not sure why it wouldn't take my screen shots of my network testing but anyway, there were a series of things I was supposed to try and then call AppleCare if nothing got better. One of the things to try was changing the DNS numbers. I did that first even though I thought that couldn't be it. It worked. I put 8.8.8.8 and 8.8.4.4 back in and now everything works just fine and dandy. One of the error messages said that my network wound't accept my DNS numbers. It used to. Any ideas?

Also, I still can't get the Ookla speed test to work. I don't know what that's all about because I've never had trouble with that, but this is the first time I've used it since d/ling Catalina. I'm done rambling.

Network diagnostic tests only check to see if there is a connection. It does not check the quality of that connection. The problem you are describing sounds very much like something amiss with your Internet Service Provider. For what it is worth you did all the right things on your end.


According to IMGUR they accept JPEG, PNG, GIF, APNG, TIFF, MP4, MPEG, AVI, WEBM, QuickTime, x-matroska, x-flv, x-msvideo, and x-ms-wmv files. The maximum file size for non-animated images (think JPG, PNG, etc) is 20MB. PNG files over 5MB will be converted to JPEGs. The maximum file size for animated images (like GIFs) and video is 200MB. Video uploads cannot be longer than 60 seconds. GIF and video files over 2MB will be converted to GIFVs, where the sound is removed. Non-animated images over 1MB for anonymous uploads and 5MB for account holders will be lossily compressed. What they will not accept, yet, is heic which Apple uses as default in iOS and and iPadOS devices to conserve space while maintaining quality.

If you were using a reputable public DNS server such a OpenDNS, Google, etc. This is additional evidence to make me suspicious of your ISP as the problem source. Lifewire has a current list of the best free and public DNS servers you might try.


I use Speedtest by Ookla and Oka WiFi Speed Test on Catalina and Big Sur without any issues. I don't know why I have two but each is informative in slightly different ways. You can run the Ookla Speedtest via your browser at Speedtest.net and it is often considered THE standard of comparison.

Network diagnostic tests only check to see if there is a connection. It does not check the quality of that connection. The problem you are describing sounds very much like something amiss with your Internet Service Provider. For what it is worth you did all the right things on your end.

Well it gave me few things to try and luckily changing the DNS worked. Actually I just added the different DNS numbers and left the rest on there.

According to IMGUR they accept JPEG, PNG, GIF, APNG, TIFF, MP4, MPEG, AVI, WEBM, QuickTime, x-matroska, x-flv, x-msvideo, and x-ms-wmv files. The maximum file size for non-animated images (think JPG, PNG, etc) is 20MB. PNG files over 5MB will be converted to JPEGs. The maximum file size for animated images (like GIFs) and video is 200MB. Video uploads cannot be longer than 60 seconds. GIF and video files over 2MB will be converted to GIFVs, where the sound is removed. Non-animated images over 1MB for anonymous uploads and 5MB for account holders will be lossily compressed. What they will not accept, yet, is heic which Apple uses as default in iOS and and iPadOS devices to conserve space while maintaining quality.


I still don't understand what Imgur had against my .png screenshots. They were just short paragraphs. Oh well.

If you were using a reputable public DNS server such a OpenDNS, Google, etc. This is additional evidence to make me suspicious of your ISP as the problem source. Lifewire has a current list of the best free and public DNS servers you might try.

The DNS servers I was using were 192.168.9.1, 208.67.220.220 and 208.67.222.222. They worked fine until yesterday. That's when I added 8.8.8.8 and 8.8.4.4.


I use Speedtest by Ookla and Oka WiFi Speed Test on Catalina and Big Sur without any issues. I don't know why I have two but each is informative in slightly different ways. You can run the Ookla Speedtest via your browser at Speedtest.net and it is often considered THE standard of comparison. [/quote]

The speedtest.net doesn't work either. I finally tried other speed tests they they work fine.

The DNS numbers are used sequentially beginning at the top of the list. If the first DNS server does not respond then it goes to the next and so on. Chances are the one that is being used is the first one on the list.


Are you sure they were PNG? and not PDF?


DITCH THE 192.168.9.1 that is an address on your local area network, specifically your router in almost all cases. That in turn passes everything that does not start with 192 to the DNS server at your ISP (192 addresses never leave the local area network). Since it is pretty obvious your ISP was in a world of hurt that would likely make that address less than useless, but because of protocol it would be the first queried and if it responded the other addresses would never be used. I programmed my router to use the OpenDNS servers (208.67.222.222, 208.67.220.220) instead of my ISPs server. The response time is faster than my ISP and I don't get some of the questionable routing, advertising, and junk that is sometimes encountered through an ISP's router.


GET RID OF THE 192.168.9.1 DNS SERVER ADDRESS and I will bet Speedtest will come back to life.

The DNS numbers are used sequentially beginning at the top of the list. If the first DNS server does not respond then it goes to the next and so on. Chances are the one that is being used is the first one on the list.

Possibly, but it was always first on the list and when I added the 8.8.8.8 etc. to the end of the list that's when it started to work.


Are you sure they were PNG? and not PDF? Yep, looking a 'em now on my desktop.


DITCH THE 192.168.9.1 that is an address on your local area network, specifically your router in almost all cases. That in turn passes everything that does not start with 192 to the DNS server at your ISP (192 addresses never leave the local area network). Since it is pretty obvious your ISP was in a world of hurt that would likely make that address less than useless, but because of protocol it would be the first queried and if it responded the other addresses would never be used. I programmed my router to use the OpenDNS servers (208.67.222.222, 208.67.220.220) instead of my ISPs server. The response time is faster than my ISP and I don't get some of the questionable routing, advertising, and junk that is sometimes encountered through an ISP's router.

Good to know. I deleted the 192.... address just incase.


GET RID OF THE 192.168.9.1 DNS SERVER ADDRESS and I will bet Speedtest will come back to life. [/quote] After I deleted the 192 DNS number, the speed test app still does not work, but it works on the website now. Thanks.

I just attempted to post a PNG on Imgur and the session locked up forcing me to quit Safari to clear the stoppage. Imgur may be having some issues on their site.

Just a few days ago, https://imgur.com/upload began looking as you see it by clicking on the link, and after clicking on "Sign In" in the pane (my only opton on the pictured page) I see the old, familiar "Drop images here" pane and have no trouble with PNGs.

Imgur seems to be going through some changes, and I can't even document what I'm experiencing coherently, but I'll say that opening an account seems to be a good approach to dealing with it.

I have an account, I was just too lazy to sign in. I will next if I have a problem next time. Thanks, Artie.

The DNS numbers are used sequentially beginning at the top of the list. If the first DNS server does not respond then it goes to the next and so on. Chances are the one that is being used is the first one on the list.

I was having the same problem today. I checked the DNS numbers, and the old ISP one is back on top. Is there a way to prevent that coming back, or will it stay at the bottom if I put it there?

Simply delete it by selecting it, clicking the minus sign at the bottom of the list, then clicking OK then click APPLY.

I did that, But it came back the next day. I have gotten rid of it once again. If it comes back, I will put it at the bottom of the list.

Open System Preferences > Network > Advanced > TCP/IP. Look at what is selected for "Configure IPv4:". If it is "Using BootP" change it to "Using DHCP". Then check the DNS settings.

It's set to DHCP and IPV4.

Move that DNS number to the bottom of the list and hope that it doesn't float to the top.

If it's at the bottom, it technically will never be accessed, since the OpenDNS and Google numbers will come into play before it.

Thanks, Artie. Yeah, that is what I wondered outloud about.

Well that eliminates one reason for the 192 DNS servers' re-appearance on the list. A mistake I have made in changing the settings in System Preferences > Network > Advanced is not clicking OK on this window and then clicking APPLY on this window. It is easy to miss the second one and if you don't click both, the changes will not stick. If there is something else at work here, I am at a loss.

Thanks. I think I clicked apply, but maybe I did miss it. We will see in the future. Thanks for all your input.