Submitting a Form (Admin / Setup Menu) results in "408 Request Timeout Please reload the form without submitting CGI parameters"

After updating from MX-V4.4.2.73 to MX-V4.7.2.19, all cameras (T24, T25, S14, S15) more and more often produce a “408 Request Timeout - Please reload the form without submitting CGI parameters” error when submitting a form.
It even occurs when you want to reboot the camera.
Using a different browser does not solve this issue.
After rebooting the camera, this error disappears for a while.
Is this a known issue?
Is there a workaround available?