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Internet works in one app but not another: DNS, proxy and route checks

Verified 1 min read

Diagnose Windows 11 name-resolution failures with Resolve-DnsName, nslookup, proxy settings, hosts file, VPN and route tests before changing DNS servers.

Tested onPro (26H2) · Build 26300.9457 · x64
E1
Build
26300.9457
Edition
Pro (26H2)
Architecture
x64
Support
Documentation (E1)
Evidence
E1Official documentation
Verified
2026-10-28
Page type
Troubleshoot

The short answer

Section titled “The short answer”

“One app works, another does not” usually means name resolution, proxy or route, not “the internet is down”. Test in this order:

  1. IP connectivity
  2. DNS resolution
  3. TCP port
  4. proxy
  5. app-specific config

1. IP connectivity

Section titled “1. IP connectivity”
Terminal window
ipconfig /all
ping 1.1.1.1
tracert 1.1.1.1

If ping by IP fails, fix the link/route/gateway first. DNS is irrelevant if packets cannot leave.

2. DNS resolution

Section titled “2. DNS resolution”
Terminal window
Resolve-DnsName example.com
nslookup example.com
Resolve-DnsName example.com -Server 1.1.1.1
  • Works with a public server but not the default: the local DNS server is the problem.
  • Fails everywhere: check the adapter DNS, VPN, hosts file, DNS Client service.
  • Works for one name only: check the record/zone, not the whole stack.
Terminal window
Get-Content C:\Windows\System32\drivers\etc\hosts
Get-Service Dnscache
ipconfig /flushdns

Do not edit hosts to “fix” a site unless you own the mapping; it is a common malware/persistence location.

3. TCP port

Section titled “3. TCP port”
Terminal window
Test-NetConnection example.com -Port 443

If DNS resolves but TCP fails, a firewall/proxy/ISP block or the service is down. Try another network (phone hotspot) to separate local from upstream.

4. Proxy

Section titled “4. Proxy”
Terminal window
netsh winhttp show proxy
Get-ItemProperty 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings' |
  Select-Object ProxyEnable, ProxyServer, AutoConfigURL

A proxy set by a VPN, malware or a corporate policy can break one app while another uses a different stack. Check WinHTTP, WinINET and the app’s own proxy setting.

5. App-specific

Section titled “5. App-specific”
  • Browser: secure DNS/DoH, proxy extension, QUIC.
  • Store/Update: WinHTTP proxy, WSUS/Intune policy.
  • Steam/Epic: launcher proxy/download region.
  • WSL: mirrored vs NAT networking.

Quick decision table

Section titled “Quick decision table”
Symptom First check
Ping IP works, name fails DNS server/adapter/VPN
Name works, HTTPS fails Proxy/firewall/port 443
One browser fails Browser DoH/proxy/extension
All browsers fail, ping works WinHTTP/WinINET proxy
Only corporate apps fail VPN/split tunnel/policy
WSL fails, Windows works WSL networking/firewall

Sources