Hello @CrankyCoder,
welcome to the Nextcloud community! 
the forum is full of similar discussions see server_migration
I recommend reading the docs regarding process and primary storage likely you find ideas
- server migration
- primary storage
- Docker .examples
- docker-compose-setup-with-notify-push-2024
- Nextcloud docker compose setup with Caddy (2024)
- Docker upgrade procedure
- Docker persistent data
- Nextcloud AiO
in short I would recommend you migrate to new system and upgrade to current version