Technical Tip: Slow GUI access when running FortiManager versions above v7.4.0 and v7.2.2

When running FortiManager versions above 7.4.0 and 7.2.2, unexpected GUI behaviour, including slowness, stalling, and disconnects, can be experienced.

This is sometimes caused by a change that was introduced in FortiManager versions 7.4.1 and 7.2.3 to support the HTTP/2.0 protocol.

Before version 7.2.3/7.4.1, the default 'apache-mode' utilized the 'prefork' mode. From version 7.2.4, the default configuration uses 'event' mode.

With HTTP/2.0, there is no strict limit on the number of concurrent requests, which can sometimes result in degraded GUI performance, particularly if the client environment imposes its own constraints.

Although HTTP/2 introduces several improvements, it can also present challenges. Issues such as head-of-line blocking and inefficient resource prioritization may negatively impact performance compared to HTTP/1. In addition, features like server push and the handling of encrypted headers by intermediate devices can introduce further complexity. The increased processing overhead required for HTTP/2 can also affect response times. As a result, there are situations where HTTP/1 may deliver better overall performance.

In these cases, it is possible to revert to the "prefork" mode using the following commands:

config system global

(global)# set apache-mode prefork

(global)# end

Note: Similar issues may also be seen with FortiAnalyzer for the same reasons. The same fix can also be applied to FortiAnalyzer.