Diagnose Windows Server NIC, Gateway and Route Connectivity Problems

Before you begin

Applicable to supported Windows Server/client environments where the named role or feature is installed. Run read-only checks first from an elevated PowerShell or Command Prompt as appropriate. Replace example hostnames, domain names, addresses, ports and paths with values from the affected environment. Record the exact error, timestamp, OS build and scope of impact.

Production safety: obtain change approval and a verified backup before modifying AD DS, DNS, DHCP, firewall, IIS, storage or Hyper-V configuration. Ensure console/out-of-band access before network or remote-access changes.

Symptoms and likely root cause

A server is intermittently unreachable, cannot reach gateway or uses wrong NIC, DNS server or default route.

Multiple default gateways, interface metrics, wrong VLAN, duplicate IP, NIC resets or multi-homed DNS registration.

Diagnostic commands

Get-NetAdapter -IncludeHidden | Sort-Object ifIndex | Format-Table ifIndex,Name,Status,LinkSpeed,MacAddress
Get-NetIPConfiguration -Detailed
ipconfig /all
Get-NetRoute -AddressFamily IPv4 | Sort-Object RouteMetric,InterfaceMetric
Get-NetIPInterface -AddressFamily IPv4 | Format-Table InterfaceAlias,InterfaceMetric,Dhcp,ConnectionState
Test-NetConnection 10.20.0.1
tracert -d 10.20.0.1

Run the commands in order and save the complete output. The commands above are intended to establish the failing layer before a configuration change is attempted.

How to interpret the results

Map production, management, backup, iSCSI and virtual NICs. Identify intended default gateway. Multiple default routes or unexpected metrics may send traffic through wrong interface. Ping failure can be ICMP filtering; test a relevant TCP service too.

Practical correction

Check cable/switch port/VLAN, NIC errors, duplicate IP and vendor driver/firmware. Correct route/metric only after confirming design. Avoid default gateway on backup/iSCSI NIC unless required. Multi-homed DNS registration needs deliberate design.

Make one change at a time. Re-run the failed diagnostic after each change so the cause-and-effect relationship is clear.

Fallback and recovery

Before remote IP/gateway changes, ensure console/out-of-band access and record old config. Change one setting at a time; restore recorded IP/routes from console if access drops.

Verification checklist

Success: correct source interface and gateway are selected; DNS and application port work after reboot/failover; no recurring NIC reset events.

• Repeat the original failing operation from the affected client/user or service.
• Test from a second approved endpoint or subnet where relevant.
• Review the relevant event log/IIS log after the fix.
• Record the change, actual result and any remaining limitation.

Frequently asked question

Should every NIC have a default gateway? Usually no. Multi-homed routing must be intentional.

Official technical reference

Microsoft Learn — get netipconfiguration

Use the official documentation for exact version support, prerequisites and any procedure that differs between Windows Server releases.

Technician field note

This runbook describes a controlled diagnostic path; it is not a universal guarantee that every environment has the same cause. If evidence does not match the expected result, stop and investigate rather than applying unrelated fixes. Do not mark the incident resolved until the original symptom is verified as cleared.