Cannot load webpages on any network, with any broswer

Hi,
I have a 2014 Macbook and I've been experiencing on and off a very annoying sluggish response in loading web pages.
They take tens of seconds to load, and in most cases the browser just gives up and displays some error message like
"There is no internet connection", "The site can't be reacherd" or "is taking too much time to respond"

Some facts:

1. It happens with ALL my browsers (Chrome, Safari, Firefox), on ALL the networks I tried (home, work, cafes, you name it...), and
as far as I can tell on ALL webpages.

2. The problem usually lasts for a few days, then it works correctly for a while, then it stops again for a few days, and so on.

3. It's not the Wifi antenna:
A speed test with speedtest.py from the terminal gives Download 49.67 Mbit/s
Upload 5.43 Mbit/s

In fact the problem persists if I turn off WiFi and use Ethernet (I tried
it on two different LAN).

4. I have an iMac on my home network and I never experienced this problem on the iMac.

I suspect it may be a problem with DNS but I don't know what to do.

Any help would be greatly appreciated.

Welcome to our forums.

It may or may not be a DNS problem. If the iMac on your home network is not having any difficulty when using the same DNS servers, then it probably is not something related to DNS. Try removing all connection information on the MacBook and create a new one to see if that helps. You could always enter new DNS information if you feel that will help. We recommend using the free Google Public DNS servers:

8.8.4.4.
8.8.8.8.

chscag said:

Welcome to our forums.

It may or may not be a DNS problem. If the iMac on your home network is not having any difficulty when using the same DNS servers, then it probably is not something related to DNS. Try removing all connection information on the MacBook and create a new one to see if that helps. You could always enter new DNS information if you feel that will help. We recommend using the free Google Public DNS servers:

8.8.4.4.
8.8.8.8.

Click to expand...

Thank you.
Indeed the iMac is using the same DNS servers and doesn't have any problem. I just changed the DNS of the Macbook to the Google Public DNS servers and the problem persists. What else could the problem be?

Sounds like a hardware issue. Maybe a defective card or the antenna cable has become disconnected or loose?

ferrarr said:

Sounds like a hardware issue. Maybe a defective card or the antenna cable has become disconnected or loose?

Click to expand...

But then how could I consistently get a download speed of around 50 Mbit/s when I test the speed with speedtest.py? (via the terminal, not the browser, of course). Also, I can download large files fast with ftp and scp, and I ping are ssh are also fast. The problem seems to be just with http...

How full is the SSD? Also you might try downloading and running Onyx. I don't know if it would help but it can't hurt. The link is listed below in my signature area.

Lisa

lclev said:

How full is the SSD? Also you might try downloading and running Onyx. I don't know if it would help but it can't hurt. The link is listed below in my signature area.

Lisa

Click to expand...

I still have 100 Gb of free space. I don't think Onyx would help. Any other ideas on how I may diagnose where the problem comes from?

If you are not running any browser extensions or antivirus that could be mucking up the works or some app that has an attitude - I agree with ferrarr (Bob) - your looking at a hardware issue.

Just for a quick check - can you download malwarebytes and run it to eliminate potential malware? You may have to let another mac download it and hopefully it will update. Other than that if you have an apple store close a trip to the genius bar and have them do a free diagnostics would be my next idea. The Apple Diagnostics might show something but the genius bar is more in depth.

Lisa

Thanks, following your suggestion I downloaded malwarebytes and eliminated 5 threats. Right now websites are loading correctly, but I don't know if it's because I restarted the computer (which sometimes solves temporarily the problem) or the eliminated threats. I keep my finger crossed that it will last. By the way I also have Sophos antivirus installed, and I checked that it wasn't the culprit.

Glad Malwarebytes helped. You will get a lot of advice that you do not need to run Sophos. On most systems it will slow it down and can cause issues. I run Sophos on my Mac Pro but ONLY because it is in a work network with other PCs. I do not run it or any other antivirus on my Macbook Air or Macbook Pro. I have found safe browsing practices, using Ghostery and Ublock Origin as browser extensions and running Malwarebytes monthly to check for issues has worked very well for me.

Lisa

Update: after two weeks without any problem, the sluggishness is back! I run again Malwarebytes but it found no threats, so there has to be another reason.
I did install Ghostery by the way. Any other ideas? Thanks.

Again as Lisa asked. Are you running any antivirus software, CleanMyMac, Mackeeper or similar?

harryb2448 said:

Again as Lisa asked. Are you running any antivirus software, CleanMyMac, Mackeeper or similar?

Click to expand...

I'm running Sophos and I checked that when I disable it, the problem persists.

Uninstall it may improve things. Use the uninstaller that came with the program.