Really struggling with Modded Minecraft Auto_CurseForge/CurseForge Server (community app)

Have had zero trouble getting a NeoForge server running (sans any modpacks), but trying to get a modpack working has been a real pain no matter which way I go.

The Minecraft app documentation is generally excellent, but I am a little stuck on how to get a modpack working. The docs walk through Auto_CurseForge and manual CurseForge, but I cannot even get a standard CurseForge server running in the first instance (bounces around deploying and stopped).

I thought maybe it was just me, so figured I would try the same for a basic NeoForge server, and it works perfectly. But adding a modpack from the CurseForge site either automatically or manually just doesn’t work. And, as said, trying with CurseForge as the launcher I can’t even get a bog standard server up.

I have tried all versions of Java that make sense (NeoForge was easy on 21 Ubuntu), so I don’t think it is that.

I feel like I must be missing something really simple, but after hours of searching and forum reading, I am no closer.

Java 21 Hotspot (Have tried 17 and 8 as well)
Type: CurseForge
Version: 1.21.1
Result: App bounces between deploying and stopped a few times before not bothering anymore

Java 21 Hotspot
Type: NeoForge
Version: 1.21.1
Result: App launches fine, and I can connect to my server

Any number of CurseForge variables to get a mod installed stops NeoForge from running. I must be getting them wrong in that case?

For example, adding:

MODPACK_PLATFORM: AUTO_CURSEFORGE
CF_API_KEY: <key, with $ escaping)>

And now my NeoForge server won’t run. I would have thought this would be a nice minimal extra step to go before getting a modpack installed, but this won’t run.

Thanks to some assistance from the docker-minecraft-server maintainer themself, itzg, it is working perfectly.

Turns out the whole time, the URL I was using was not for the modpack, but the mod, hence the falling over once I tried to setup AUTO_CURSEFORGE.

That’s not really a solution.
Please show the actual correct text you added to get it running.

I’m trying to get a server set up for my son. He has a ton of custom mods. I was able to configure and run a standard Forge server, but once I put all the config files and mod files in their folders it’s been stuck Deploying for about 12 hours?

Is there a certain way to get mods installed?