520 Error on subdomain

Thanks in advance for your help!

I’m running a personal domain (no site) and use subdomains to point to devices in my home network.

I have been using Cloudflare and assigning subdomain DNS records to point to my public IP address, which then connects through a reverse proxy administered by my Load Balancer and redirects each sub to a device on my network.

What currently has been working is my QNAP NAS, Proxmox Server, Load Balancer (hosted on my Proxmox), Host Router and AP Router. All work perfectly.

Today I configured a Music Server as a Docker Container on my NAS and gave it a static IP address and port on my LAN then setup Cloudflare as usual. The server works great locally but I can’t access it through the subdomain without getting the 520 Error: SSL_ERROR_RX_RECORD_TOO_LONG.

Reading through the docs on CF this error is typically: “SSL received a record that exceeded the maximum permissible length.” This generally indicates that the remote peer system has a flawed implementation of SSL, and is violating the SSL specification.

I’m wondering if this is a Docker Issue, NAS Issue or other and if there is any work around besides setting this up again and hosting it on my Proxmox server?

Thanks in advance (again).

Does the issue persist if you pause Cloudflare on the zone or set the DNS record to unproxied :grey:?

I unproxied the DNS record and the error remains.

Using a different browser I am told that the subdomaining is sending no data.

That indicates the issue is with your setup rather than Cloudflare. Just make sure you cleared DNS cache after unproxying :grey: the DNS record.

Non-Cloudflare issues are generally out-of-scope of this forum, but I can take a quick look if you share the domain.

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How can I share without publicly posting on this forum?

And thank you!