How to prevent my external monitor from turning off when the system is idle

When I'm using my laptop if I don't use it for a while, the laptop's screen goes off and the external monitor turns off by itself. I'm trying to prevent my second monitor from turning off, and I want it to remain a blank black screen for a given period of time when the system passes to an idle state. I'm connecting a second screen to my laptop by an HDMI cable to an LCD screen. I use Debian 12 (bookworm), and I use gnome-43.9 desktop environment. I also use the Wayland windowing system. I tried xset s off and it didn't effect anything. There was no error when executing this command. When I tried xset -dpms I got this error message: server does not have extension for -dpms option I looked up similar questions and other Stack Exchange forums, but I couldn't find a way to get around this problem.