Boot Mint21 with display turned off

[FumbleFingers]

Since upgrading from Mint 20 to Mint 21, my Shuttle DH310 mini PC doesn't boot properly if it doesn't have a monitor attached (and turned on). Sometimes I don't need the display because I just want to connect to the Shuttle via SSH to do something at the command line level.

Worse than that, my brother has a similar set-up with two mini PCs connected to one HDMI splitter with a "toggle" button that controls which machine's output is sent to his TV. If the toggle isn't connecting the right PC, it won't boot.

Below is what I hope is the relevant "System Information" from my Shuttle DH310. Is there anything easy I can do to force correct video output before connecting/turning on the display?

Machine:
Type: Desktop System: Shuttle product: DH310 v: 1.0 serial: Mobo: Shuttle model: FS310 v: 1.0 serial: UEFI: American Megatrends v: 1.11 date: 02/08/2021
CPU:
Info: 6-core model: Intel Core i5-8400 bits: 64 type: MCP arch: Coffee Lake rev: A cache: L1: 384 KiB L2: 1.5 MiB L3: 9 MiB Speed (MHz): avg: 3856 high: 3899 min/max: 800/4000 cores: 1: 3799 2: 3892 3: 3899 4: 3899 5: 3852 6: 3798 bogomips: 33599 Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Graphics:
Device-1: Intel CoffeeLake-S GT2 [UHD Graphics 630] vendor: Holco Enterprise Co /Shuttle CometLake-S driver: i915 v: kernel ports: active: DP-2 empty: DP-1,DP-3,HDMI-A-1 bus-ID: 00:02.0 chip-ID: 8086:3e92 Display: x11 server: X.Org v: 1.21.1.4 driver: X: loaded: modesetting unloaded: fbdev,vesa gpu: i915 display-ID: :0 screens: 1 Screen-1: 0 s-res: 3840x2160 s-dpi: 96 Monitor-1: DP-2 model: HISENSE res: 3840x2160 dpi: 140 diag: 1321mm (52") OpenGL: renderer: Mesa Intel UHD Graphics 630 (CFL GT2) v: 4.6 Mesa 22.2.5 direct render: Yes

[SMG]

Below is what I hope is the relevant "System Information" from my Shuttle DH310. Is there anything easy I can do to force correct video output before connecting/turning on the display?

Please open the System Reports app and click the System Information tab on the left. Your computer's information should come up in the right pane. Then click the Copy button in the lower right and paste the results into a reply window here so we can see how Linux Mint views your hardware.

Did you do an in-place upgrade from LM20.3 to LM21 or did you do a fresh install of LM21?

[motoryzen]

Greetings FumbleFingers

Adding to SMG's point, you didn't do anything wrong imo.

I think the step 5 of how to get help should have the directions she specified instead. Easier for a beginner in the Linux world who is more used to gui than terminal, and narrows down getting 99.99% the same complete info.