Description of the issue & error
Every year an application creates on multiple occasions in the year (March-April and November) several PDF files using the Ultimate PDF component. Since this year, the application has run into issues with creating the PDF. The smaller PDFs (i.e. less data, less pages, less images) are still easily created, however the PDFs that contain more data now lead to 502 Bad Gateway Error. Every year extra data is added to the PDF. Last year a PDF that was containing 468 pages was created nicely. However, this year the PDF will approximately have 30 pages more and now leads to a 502 Bad Gateway Error. In service center, we see the following stack information:

Installed version
Ultimate PDF 12.0.1 (since December 2023)
Ultimate PDF for Traditional Web 12.0.1 (since December 2023)

How is Ultimate PDF used in the application?
When pressing a button on the screen an action is called that will wake up a timer. In this timer the ScreenToPDF action is called. The timeout of this timer is the default of 20min. The Site Property DefaultBrowserTimeoutSeconds is enlarged to 600 seconds. In the timer logging we often see that an error occurs somewhere between 2 and 7min, and then it tried to restart the timer. After the third try the 502 Bad Gateway Error is shown on the screen. Also, calling the screen of which we want make a PDF from will result after some time in a 502 Bad Gateway Error.

Question
What is the cause of this 502 Bad Gateway Error and how can we solve it?

Thank you for your help.