HELP! Strange Internet access problems on just one of my computers.

[j.erbes]

I have limited access to the Internet sites on one of my computers but not the other.

This started three days ago.
On my wireless-connected laptop I have no problems at all.
On my ethernet-connected desktop I can only access some of the Internet.
Both Firefox and Internet Explorer give me the same exact problems listed below.

The sites I CAN access include:
google.com, att.com, facebook.com (no sound), wikipedia.com, youtupe.com (no sound), CDC.com, NIH.com, mozilla.org.

The sites that I CAN'T access include:
yelp, newegg.com, ebay.com, amazon.com, my mail server, download.mozilla.org, and a whole bunch of various other sites.

Additionally, I can't PING anything from the desktop (not even my own IP address.)
PING works fine on the laptop.

Note that I CAN access mozilla.org but NOT download.mozilla.org

The message I get for about 80% of the sites I try is:
"We can't connect to the server at xxxxx.xxxxx.xxx"

These are the things that I have tried that have NOT helped.
1. It is not within Firefox or Internet Explorer. They both give identical results or non-results.
2. I've rebooted the computer multiple times.
3. I did a "Restore Firewall to Default" in Windows Defender.
4. Temporarily turning off Windows Defender Firewall didn't help.

I am running Win 10 Pro 64-bit with all updates installed. 10.0.17134

 

[kanewolf]

What happens when you connect your laptop via wired? Work normal or have problems? Do you have the DNS setting on your desktop set to "obtain automatically"? What if you manually enter the google DNS 8.8.8.8 and 8.8.4.4 ?

 

[j.erbes]

What if you manually enter the google DNS 8.8.8.8 and 8.8.4.4 ?

I'll try plugging it in to my switch.
What do you mean by the above?

 

[kanewolf]

You can specify a DNS (dynamic naming service) provider on both your router and on an individual device connected to your router. The IPv4 properties of your wired adapter on your PC allow you to override the router provided DNS addresses. If you DO override the DNS provided by your router what happens?
Here is an article on setting the DNS in windows 10 -- https/www.windowscentral.com/how-change-your-pcs-dns-settings-windows-10

 

[j.erbes]

What happens when you connect your laptop via wired? Work normal or have problems? Do you have the DNS setting on your desktop set to "obtain automatically"? What if you manually enter the google DNS 8.8.8.8 and 8.8.4.4 ?

OK
I connected the desktop ethernet cable to the laptop and the laptop works just fine.

DNS on the desktop was set to 'obtain automatically'.
I changed it to use 8.8.8.8 and 8.8.4.4.

The desktop 'seems' to be working OK now.
Why did changing the DNS server to Google apparently solve my problem?

 

[kanewolf]

Your symptoms sounded like a DNS problem. You could check to see if you had manually altered the DNS on your laptop. What I would recommend you do is to change the DNS settngs on your ROUTER so that all your devices use the google DNS servers.

 

[j.erbes]

Thanks a bunch.
I'll go and change the DNS on the router.
Strangely, the DNS on the laptop is set to automatic.