Mac Mini 2012 HDMI connection to external Dell screen disconnects sporadically

I am having issues with the HDMI connection from my Mac Mini to my external Dell screen. It sometimes disconnects briefly and then reconnects again. The Mac Mini only supports HDMI as it is an older model, but it now feels like the graphics card or the HDMI output port is having issues.

Specs:

Mac mini (Late 2012)

macOS Catalina 10.15.7 (19H2026)

2.6 GHz Quad-Core Intel Core i7

Intel HD Graphics 4000 1536 MB

DELL S2721QS Display

30.5-inch (1920 x 1080)

Intel HD Graphics 4000 1536 MB graphics

default settings for display

Any ideas how I can debug this?