Why Can’t I Access My Admin Page or Upload Images From Inside My Network?

Overview

If your Admin page loads correctly outside your network but fails to load or upload images inside your building, the cause is usually how your router handles the server’s public domain name from within the same network.

This behavior is known as NAT loopback (also called hairpin NAT or NAT reflection).

Inside your network, your devices may fail to reach your site’s public domain, even though the server itself is functioning correctly.

This guide covers:

• A quick workstation fix (Windows or Mac)

• How to confirm the root cause

• A network-wide permanent fix

• What to do if image uploads still fail

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Symptoms You May See

• The Admin page does not load internally

• The Admin page loads but image uploads fail or time out

• The system works normally from home, mobile hotspot, or off-site

These symptoms confirm the issue is network-related, not a server or software failure.

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Quick Fix: Create a Local DNS Override (Windows)

Perform these steps on any affected Windows PC.

1. Close all browsers

Completely exit Chrome, Edge, Firefox, etc.

2. Open Notepad as Administrator

1. Click the Start menu

2. Type Notepad

3. Right-click >  Run as administrator

4. Click Yes when prompted

3. Open the HOSTS file

In Notepad:
File > Open…

Paste this path: C:\Windows\System32\drivers\etc\hosts

Change the file type (bottom right) to All Files
Select the file named hosts > Open

4. Add this line at the bottom

Replace the placeholders with your actual server IP and domain:

<LOCAL_SERVER_IP> <PUBLIC_DOMAIN_NAME>

Example:

192.168.1.10 example.clubspeedtiming.com

5. Save the file

File → Save

6. Flush DNS

Press Windows Key + R, type cmd, press Enter.
In the command window:

You should see Successfully flushed…

7. Test the Admin page

Go to:

If it loads and uploads work normally, the issue is confirmed as NAT loopback.

Repeat these steps on any additional PCs that need access.

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Quick Fix: Create a Local DNS Override (Mac)

Note: Steps follow Apple’s recommended method for editing the HOSTS file. Behavior may vary slightly by macOS version.

1. Open Terminal

Applications > Utilities > Terminal
(or search “Terminal” in Spotlight)

2. Open the HOSTS file with admin rights

Run:

Enter your Mac password (the cursor will not move, this is normal).

3. Add this line at the bottom

4. Save and exit

Press:

• CTRL + O

• Enter

• CTRL + X

5. Flush the DNS cache

Run:

(No success message will appear.)

6. Restart your browser and test

Try the Admin page again and attempt an image upload.

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If Image Uploads Still Fail

If the Admin page loads but image uploads still don’t complete, the issue is usually one of the following:

1. The upload handler still cannot resolve the public domain internally

Even when the main page loads, image upload endpoints may redirect to paths that still require correct internal domain resolution.

2. The image file itself

Possible issues include:

• File size too large

• Unsupported file format

• Browser caching conflicts

To confirm the exact cause, please send us the image file you're attempting to upload.
We will run a direct one-to-one test against your server to identify whether the issue is:

• File format

• File size

• Upload handler limits

• Remaining local network/DNS issues

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Permanent Network-Wide Fix (Recommended)

Share this section with your IT provider or network administrator.

To prevent issues across all devices, configure the router/firewall so that:

This can be done by:

• Enabling NAT loopback / hairpin NAT / NAT reflection
• Creating a local DNS override or host record
  • mapping the public domain to the local server IP.

Once configured, all internal devices will resolve the domain correctly without needing HOSTS file changes.

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Need Assistance?

If you'd like us to verify the setup or provide a test using the exact image you're trying to upload, feel free to send it, we’re happy to help get everything fully working again. 😊