Cannot negotiate ALPN protocol "acme-tls/1" for tls-alpn-01 challenge

General
1

I’m trying to create a Certificate from Fortigate Firewall over Let’s encrypt, and I’m getting the following error: Cannot negotiate ALPN protocol “acme-tls/1” for tls-alpn-01 challenge

Is there anything that I need t set up on Cloudflare side since ?

2

I cannot ever see the TLS-ALPN-01 challenge working with an :orange: hostname.

You can try and use the dns-01 capability of your FortiOS device, or change to :grey:.

What is the use case where you need your FortiOS to be :orange:?

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3

Hi Michael

I do not have my hostname proxied. I tried to add multiple different subdomain names to add in A record but got the same error

4

I was able to fix the issue; in Firewall, HTTPS port needs to be default in order for the Certificate update to work. So it can not be anything else except port 443

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