Fixing LAN Connection (Port 9999) Issues

If your phone cannot connect to your PC via LAN, please follow these 3 steps to resolve the issue.

Step 1: Allow Port via Command (Recommended)

As a developer or power user, using PowerShell is the fastest way.

1. On Windows 11, right-click the Start menu and select Terminal (Admin) or PowerShell (Admin).
2. Paste and run the following command to allow port 9999 inbound:

New-NetFirewallRule -DisplayName "Allow Port 9999" -Direction Inbound -LocalPort 9999 -Protocol TCP -Action Allow

After running this, test the connection on your phone again.

Step 2: Check Network Profile (Often Overlooked)

If step 1 didn't work, your network might be identified as "Public". Windows blocks most custom ports on Public networks.

1. Open Settings -> Network & internet.
2. Click on Ethernet or Wi-Fi at the top.
3. Under "Network profile type", you must select "Private".

Note: If it is set to Public, Windows will silently drop inbound connections even if firewall rules exist.

Step 3: Remove Residual "Block" Rules

If you accidentally clicked "Cancel" on the initial Windows Security Alert, the system created a Block rule. Block rules override Allow rules.

1. Press Win + R, type wf.msc and press Enter.
2. Click Inbound Rules on the left.
3. Sort by "Local Port", find any rules for 9999 or rules containing the program name.
4. If you see a red Prohibitory icon, right-click -> Delete.

Ultimate Fallback: Registry Edit (100% Effective)

If PowerShell fails or the Settings app is locked, you can force the Private profile via Registry:

1. Press Win + R, type regedit.
2. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\Profiles
3. Check the subfolders for your current network name in the ProfileName value.
4. Double-click Category on the right and change its value to 1 (1 = Private, 0 = Public).
5. Click OK. The change applies immediately.