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

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

**Tested on**

- Build: 26300.9457
- Edition: Pro (26H2)
- Architecture: x64
- Evidence: E1
- Verified: 2026-10-28

## 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

```powershell
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

```powershell
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.

```powershell
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

```powershell
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

```powershell
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

- 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.

> **Caution: Do not “fix” DNS by disabling security**
>
> Do not disable Windows Firewall/Defender or install a random “DNS booster”. Change one setting, test, revert if it does not help.

## 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

- [Microsoft — DNS overview](https://learn.microsoft.com/en-us/windows-server/networking/dns/dns-top)
- [Microsoft — Test-NetConnection](https://learn.microsoft.com/en-us/powershell/module/nettcpip/test-netconnection)

---

Source: https://windows.homes/en/windows/fixes/dns/