Logged in but unable to access sites

Hello,

A home-built Ryzen Threadripper I machine with Windows 10 worked well for several years. Today, Chrome failed to display web pages (“ERR_CONNECTION_CLOSED” error), Edge fails, and Thunderbird email client also fails to connect. I reset the modem, which is connected via a short ethernet cable to the computer. I restarted the computer, but the problem persists. The device normally shows as connected and the Windows troubleshooter does not find any issues.

Then I discovered that I could ping sites at will using dotted addresses. This suggested to me that the connection is ok. Then I discovered that I could ping named sites (ping google.com). Packets were passed back and forth fine. This suggested to me that the DNS was correct, but a mystery to me. I changed the DNS automatically assigned to Google (75.75.75.75) to IPv4 and did the same for IPv6. Nothing has changed, it still gives an “ERR_CONNECTION_CLOSED” error.

I ran an IPCONFIG /ALL and the report was:

Windows IP Configuration

   Host Name . . . . . . . . . . . . : nrel-rboone18
   Primary Dns Suffix  . . . . . . . : cnrdom.ColoState.EDU
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : cnrdom.colostate.edu
                                       warnercnr.colostate.edu
                                       cnr.colostate.edu
                                       nrel.colostate.edu
                                       colostate.edu

Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . : hsd1.co.comcast.net
   Description . . . . . . . . . . . : Intel(R) I211 Gigabit Network Connection
   Physical Address. . . . . . . . . : 30-9C-23-28-65-C6
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   IPv4 Address. . . . . . . . . . . : 10.0.0.112(Preferred) 
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Tuesday, May 17, 2022 3:12:34 PM
   Lease Expires . . . . . . . . . . : Thursday, May 19, 2022 4:44:25 PM
   Default Gateway . . . . . . . . . : 10.0.0.1
   DHCP Server . . . . . . . . . . . : 10.0.0.1
   DNS Servers . . . . . . . . . . . : 75.75.75.75
                                       75.75.76.76
   NetBIOS over Tcpip. . . . . . . . : Enabled

Thank you for your help,

Excited