I don't have a Synology NAS and it's weird that you can manually run it but it doesn't work with Kamal. Personally, I don't think a NAS is a good place to put containers/VMs. Mainly because when you have file systems like ZFS, I'd want the NAS to be able to allocate as much RAM as it can to ARC. The machine that I used on this episode was an Intel Ultra 7 155H ASUS NUC. https://www.asus.com/us/displays-desktops/nucs/nuc-mini-pcs/asus-nuc-14-pro/

Additional comment about the video. I'm not sure if I conveyed it well, but one of the awesome things about using Cloudflare Tunnels is that you don't have to make any changes to your network, including opening up any ports on your firewall/router. This means that you could run this on your home network or even a school network (assuming that they're not blocking certain kinds of traffic). But always check with your ISP and/or provider to see if you're within their terms of use.

Another cool thing about this approach is that if you do have a Dynamic IP Address then everything will continue to work if your ISP gives you a different IP. You won't have to go into your DNS provider to update IP Addresses. This is because the Cloudflare Tunnel initiates an outgoing request to Cloudflare's servers and keeps a connection open.

That's strange. I haven't come across that issue. I wonder if there are any other JS errors on the page that is preventing the checkout from loading.

Make sure that you are setting up the password environment variable in the .kamal/secrets and the rails credentials.

The only env var I have in my bashes is the kamal registry password as that is shared between all my apps.

In the .kamal/secrets, you could try to copy/paste the command that you're using to set the POSTGRES_PASSWORD to make sure that it's returning the expected value.