FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.

This article describes when remote access to Microsoft Windows is hosted behind the FortiGate, causes the FortiGate to become unresponsive during the RDP session Scope.

Scope FortiGate

When trying to perform remote access to the Microsoft Windows hosted behind the FortiGate, the client will be noticed were trying to access via UDP port 3389 instead of TCP 3389 via FortiGate FortiView sessions.

The client are found 'spamming' huge UDP 3389 traffic, and cause the Microsoft RDP and FortiGate freezes/slow


The solution is to either:


1)Create a new FortiGate firewall policy to deny Microsoft RDP via UDP port 3389.


2)  Follow the solution provided by third party (credit).
(*Take notes that this third party website is not manage by Fortinet).


Related link.


Technical Tip: Windows RDP connection dropped: