You connect your USB-C dock to Ethernet and everything works normally.

Windows shows the network as Private, your printer is available, and local file sharing works.

Then you disconnect the dock and reconnect it later.

Suddenly Windows says:

Public network

The internet may still work, but network discovery, file sharing, printers, or applications that depend on Private-profile firewall rules may stop working.

Does that mean the USB-C dock or Ethernet connection is broken?

Usually not.

Public vs. Private describes how Windows classifies and trusts the network—not whether the Ethernet hardware itself is working.

The best way to troubleshoot this is to check whether Windows still recognizes the same Ethernet connection after each dock reconnect.

Why Can Ethernet Work While Windows Says “Public”?

Windows assigns connected networks a category:

• Public
• Private
• DomainAuthenticated on managed domain networks

According to Microsoft's Windows network settings guidance, newly detected Windows 11 networks are normally treated as Public by default.

A Public profile is more restrictive. Windows limits discovery and sharing because it assumes the network may not be trusted.

A Private profile is intended for trusted home or workplace networks where you may want PCs, printers, and other devices to discover one another.

That means this combination is possible:

Ethernet connected ✓

Internet works ✓

Network profile = Public

The problem may be the network profile rather than the Ethernet link.

Run a Three-Reconnect Test

Instead of manually changing Public back to Private every time, compare what Windows sees across several reconnects.

Reconnect #1: Record the Working State

Connect:

Laptop → USB-C Dock → Ethernet

Open PowerShell and run:

Get-NetConnectionProfile

Record:

• InterfaceAlias
• InterfaceIndex
• NetworkCategory
• network name

Then run:

Get-NetAdapter | Select-Object Name, InterfaceDescription, MacAddress, ifIndex, Status

Record the Ethernet adapter's:

description + MAC address + interface index

For example:

InterfaceAlias    Ethernet 3
InterfaceIndex    18
NetworkCategory   Private

This is your known-good baseline.

Reconnect #2: Use the Same Dock and Cable

Disconnect the dock for several seconds.

Reconnect it to the same laptop port using the same Ethernet cable.

Run:

Get-NetConnectionProfile

again.

Now compare the result.

Same Ethernet Adapter, but Private Becomes Public

Example:

Before:
Ethernet 3
Private

After:
Ethernet 3
Public

If ordinary internet access still works, this points more toward Windows network-profile handling than an RJ45 failure.

For a network you genuinely trust, Windows 11 allows you to change the profile under:

Settings → Network & internet → Ethernet → Network profile type

Select:

Private network

You can also use:

Set-NetConnectionProfile -InterfaceAlias "Ethernet 3" -NetworkCategory Private

Microsoft documents Set-NetConnectionProfile as the PowerShell command for changing an existing connection's network category.

But if it returns to Public after every reconnect, keep testing. The category change may be a symptom rather than the root cause.

Reconnect #3: Check Whether the Network Identity Changed

Reconnect the dock once more and compare:

There are two useful patterns.

Pattern A: Same Adapter, Same MAC, Different Category

If Windows consistently sees:

same Ethernet adapter

same MAC address

but:

Private → Public

focus on:

• Windows network-profile recognition
• local security policy
• firewall policy
• enterprise management settings

The physical dock Ethernet interface may be working correctly.

Pattern B: Connection Identity Changes

If the interface information or network context changes after reconnecting, Windows may treat the connection differently and apply its default Public behavior.

Do not judge this only from names such as:

Ethernet 2

Ethernet 3

Ethernet 4

Windows can rename interfaces over time.

Compare the adapter description and MAC address before concluding that different Ethernet hardware is being detected.

Why the MAC Address Matters

A USB-C dock with Ethernet contains its own network interface and MAC address.

That identity can matter on:

• corporate networks
• university networks
• DHCP reservations
• NAC systems
• MAC allowlists

If Windows network classification changes at the same time that the presented Ethernet identity changes, investigate the adapter identity separately.

The LENTION guide on USB-C hub Ethernet MAC addresses and corporate network rejection covers that case in more detail.

The distinction is:

MAC address identifies the Ethernet interface.

Public or Private describes Windows' trust level for the connected network.

They are related to different parts of the network stack.

Why File Sharing May Stop Even Though Internet Still Works

Suppose after reconnecting:

Internet works

but:

shared folder fails

printer disappears

network discovery stops

This does not necessarily mean the dock lost Ethernet connectivity.

Windows Firewall can apply different rules depending on whether the active network is Public or Private.

A connection that changes from:

Private → Public

may therefore lose discovery or sharing behavior while normal outbound internet traffic continues.

Before creating new firewall rules, run:

Get-NetConnectionProfile

If it says:

NetworkCategory : Public

check the network classification first.

Do not solve an incorrectly classified trusted network by broadly opening file-sharing access on the Public firewall profile. That could expose the laptop when it later connects to a genuinely public network.

Corporate Network? Watch for DomainAuthenticated

Company-managed computers need slightly different treatment.

Windows may normally classify the office network as:

DomainAuthenticated

Microsoft notes that DomainAuthenticated cannot simply be manually selected using Set-NetConnectionProfile. Windows assigns it when the computer successfully authenticates to the domain.

So if the normal state is:

DomainAuthenticated

but reconnecting the USB-C dock produces:

Public

do not immediately force it to Private.

Instead investigate:

Ethernet connection

→ IP configuration

→ DNS

→ domain controller reachability

→ domain authentication

If the company network also uses wired authentication, the problem may occur even earlier. The separate guide on 802.1X Ethernet authentication through USB-C docks covers that scenario.

Keep Profile Problems Separate From Ethernet Problems

This article applies when:

Ethernet connects

internet works

but:

Windows shows the wrong network profile

If instead the symptoms are:

• no Ethernet adapter
• no IP address
• repeated disconnects
• RJ45 link drops
• unexpected 100Mbps speed
• no internet even without profile issues

start with the USB-C hub Ethernet troubleshooting guide.

A useful rule is:

Working Ethernet + wrong Public/Private category = investigate the profile first.

Missing or unstable Ethernet = investigate the physical/data connection first.

Use a Consistent Ethernet Setup When Testing

When repeating the three reconnects, keep the network hardware unchanged.

For a typical desk setup, a USB-C hub with Gigabit Ethernet, three USB 3.0 ports, and 4K HDMI gives you a consistent wired-network path while also supporting everyday peripherals and display output.

The LENTION CB-C25 provides:

• Gigabit Ethernet up to 1000Mbps
• three USB 3.0 ports up to 5Gbps
• HDMI up to 4K@30Hz

A typical connection becomes:

Laptop → USB-C Hub → Ethernet + USB Devices + Display

That makes it suitable for repeating the same reconnect test under a realistic desk setup.

However:

The hub provides the Ethernet interface; Windows still decides whether the connected network is Public, Private, or DomainAuthenticated.

Changing hardware should not be presented as a direct fix for a Windows network-profile problem.

Use This Result Table

This table helps turn:

“My dock keeps changing the network.”

into a much more specific diagnosis.

Quick Answers

Why does Windows change USB-C dock Ethernet to Public?

If Windows treats the reconnected network as new or differently recognized, it may apply the default Public profile.

Does Public mean the Ethernet adapter is broken?

No. Public is a Windows security classification. Ethernet can still have a valid IP address and full internet access.

How do I check the current network profile?

Run:

Get-NetConnectionProfile

Then check:

NetworkCategory

Can I change Public to Private?

Yes, for a trusted non-domain network, through Windows Settings or Set-NetConnectionProfile.

Why does file sharing stop after reconnecting the dock?

If the network changes from Private to Public, Windows discovery and firewall rules may become more restrictive.

Should a company domain network be manually changed to Private?

Usually not. If it should normally appear as DomainAuthenticated, investigate domain authentication instead.

Final Takeaway

If USB-C dock Ethernet keeps changing to Public Network after reconnecting, do not immediately replace the dock or Ethernet cable.

Compare three reconnects:

Profile

→ Adapter

→ MAC Address

→ Network Identity

The key rule is:

Public vs. Private describes Windows' network trust and firewall context—not Ethernet hardware health.

If:

same adapter + same MAC + profile changes

investigate Windows profile or policy behavior.

If:

network identity changes

investigate how Windows recognizes the Ethernet interface.

If:

DomainAuthenticated becomes Public

investigate corporate network authentication instead of forcing Private.

And if:

Ethernet itself stops connecting

move back to RJ45, USB, driver, or cable troubleshooting.

That separation keeps the diagnosis focused and prevents a Windows network-profile problem from being mistaken for a failed USB-C dock.