intermittent internet - network configuration keeps on changing

Question

Level 1

78 points

intermittent internet - network configuration keeps on changing

I keep on losing browser internet connectivity every few minutes. Some sort of DNS error. "Running OS 10.12.6. Every few minutes Internet goes out. In Network Diagnostics, Internet and Service radio buttons are red. Hit START OVER. Starts the system check. As Diagnostics runs, on either on WiFi Settings or Network Settings, I get the message "your network configuration has changed" and Internet back up. This happens on all browsers - safari/chrome/firefox This is not an ISP issue as other OSX and IOS devices on the same LAN have no issue. I have tried creating new Locations - wifi only, ethernet only, wifi ethernet in a prescribed fashion - they all display this intermittent behavior. I opened up a terminal window and ran "dig google.com": half the time there is a quick successful response, and half the time it times out ";; connection timed out; no servers could be reached" Any ideas? Thanks!

iMac, macOS High Sierra (10.13.2)

Posted on Dec 28, 2017 8:06 PM

Reply

Answer 1

Dec 28, 2017 8:22 PM in response to akfromnyc

One way to determine if this is a DNS problem or a connectivity problem is to:

open Terminal
type the command "ping 8.8.8.8" and then hit return
you will see a continuous list of ping results that should look something like "64 bytes from 8.8.8.8: icmp_seq=80 ttl=54 time=29.839 ms" if you have good connectivity
move the Terminal window to the side and let the pings continue until you go through one of your lost connections
if the pings continue to be successful during your connectivity failure, then you may indeed be having a DNS issue
if the pings fail during your connectivity failure, then you are having a connectivity issue and not a DNS issue
Once done troubleshooting you can type control+c to stop the pings in Terminal

If it does seem to be DNS, then set your DNS servers in the Network preference pane to something other than your current DNS. Using OpenDNS (208.67.222.222, 208.67.220.220) servers is a great choice, or Google DNS (8.8.8.8, 8.8.4.4).

If it's not DNS then try checking your hardware using Apple Diagnostics:

How to use Apple Diagnostics on your Mac - Apple Support

Reply

Answer 2

Dec 28, 2017 8:19 PM in response to akfromnyc

Restart computer but mash "D" while it is starting up. This will open diagnostics and give you an error code if anything is wrong.

Reply

Answer 3

akfromnyc Author

Level 1

78 points

Dec 29, 2017 7:26 AM in response to FishingAddict

Thanks for your detailed response - much appreciated! ping is continuously successful, even while the problem occurs, so as you say we can rule out connectivity. I added two DNS servers - one google and one OpenDNS. Very subjectively, it felt that things got better for a while, but the problem is back. The problem has to be isolated to this iMac (versus a global issue) because other devices - including a MacBook - do not have problems, on the same network. Also, i can go to random websites on my iphone safari browser WHILE the imac browser is having DNS problems. Any further thoughts - thanks!

Reply

Answer 4

Eric Root

Level 10

685,603 points

Dec 29, 2017 8:58 AM in response to akfromnyc

Something to try.

Might be a corrupt .plist.

Do a backup, preferably 2 backups on 2 separate drives.

Quit System Preferences.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Select Library. Then go to Preferences/com.apple.systempreferences.plist. Move the .plist to your desktop.

Restart the computer, open the application, and test. If it works okay, delete the plist from the desktop.

If the application is the same, return the .plist to where you got it from, overwriting the newer one.

Thanks to leonie for some information contained in this.

Reply