Blank WebGUI ... But only from web-browser SSL RA-VPN

[Fernst]

Hello!
I'm aware of Blank WebGUI but my issue is ONLY when accessing PVE GUI when using Fortigate SSL-based RA-VPN via web-browser - internal access is fine.
As per screenshot, I'm seeing "501 no such file '/PVE/StdWorkspace.js" and TCP FIN from the PVE server.
Advice?
R's, Ferenst.

 

[Elhoom]

It sounds like you're experiencing an issue where the Proxmox WebGUI isn't loading correctly when accessed through a Fortigate SSL-based RA-VPN, but it works fine when accessed internally. The "501 no such file '/PVE/StdWorkspace.js'" error, along with the TCP FIN from the Proxmox server, suggests that there might be a problem with how the VPN is handling or filtering web traffic.

Here are a few suggestions to help troubleshoot and potentially resolve the issue:

1. Check SSL Inspection Settings on Fortigate​

• If SSL inspection is enabled on your Fortigate firewall, it could be interfering with the SSL traffic between your web browser and the Proxmox server. Try disabling SSL inspection for the Proxmox server’s IP range or URL and see if that resolves the issue.

2. Browser Cache and Security Settings​

• Sometimes, browser caches or specific security settings can cause issues with accessing SSL-based interfaces. Clear your browser cache or try accessing the GUI using an incognito/private window.
• Additionally, try a different browser to see if the issue persists.

3. Verify Web Proxy and Firewall Rules on Fortigate​

• Make sure that your Fortigate configuration does not have any web filtering or proxy rules that could be blocking or altering the traffic between your VPN-connected device and the Proxmox server.
• Specifically, check if any JavaScript or web resources are being filtered or blocked.

4. Check for JavaScript or Resource Errors​

• The error message suggests that the browser is trying to access a JavaScript file (StdWorkspace.js) that isn't being served. This could be due to an issue with how the VPN handles HTTP/HTTPS traffic.
• Use the browser’s developer tools (usually accessed via F12) to see if there are additional errors in the console when trying to load the page. This can give more clues about which resources are failing to load.

5. Disable HTTP/2 (if enabled)​

• Sometimes, HTTP/2 can cause compatibility issues with certain web applications when accessed over VPNs. Try disabling HTTP/2 on your browser or through the Fortigate settings, if possible, to see if it makes a difference.

6. Use a Different VPN Client​

• If none of the above work, try accessing the Proxmox WebGUI using a different VPN client or method (e.g., OpenVPN instead of SSL-VPN) to determine if the issue is specific to the Fortigate SSL-VPN.

If you manage multiple browser profiles or frequently switch network settings, you might consider using an anti-detect browser like Multilogin, which can help manage different browser environments and network settings seamlessly.

I hope one of these suggestions helps! Let me know if you need more detailed guidance.