Debian 9 Laptop - external HDMI screen not detected

I’m running debian 9 on a ThinkPad W530. I recently tried connecting an external HDMI monitor to it but there’s just "No signal". I also have windows installed, it works just fine there. I saw some threads like this but figured i should ask myself to be safe.

Also, i feel like i should mention, when the system is booting up, there’s this short period of time before the login screen where the screen actually works and prints the same thing as the laptop screen.

Thanks in advance, I’ll provide additional information when needed.