Auto-validation process is failing on Plesk intermittently with Timeout during connect (likely firewall problem)

[Maxwell]

Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. crt.sh | example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.

My domain is:
Details - https://acme-v02.api.letsencrypt.org/acme/authz-v3/40197409080

I ran this command:
Selected for autorenewal from within Plesk

It produced this output:
Invalid response from https://acme-v02.api.letsencrypt.org/acme/authz-v3/40197409080.
Details:
Type: urn:ietf:params:acme:error:connection
Status: 400
Detail: Fetching xxxxxxxxxxxxxxxxxxx/.well-known/acme-challenge/8GT38fHu8_U1U8cx5ns_UZL1VMI5USd8USo6Psa0mqE: Timeout during connect (likely firewall problem)

The auto-renewal is failing with such errors for multiple domains hosted on the server intermittently. The port 80 and 443 are open for the world and other online tools are able to access the same URL during the same timeframe. Invoking the process manually multiple times resolves the issue. We are getting 200 status code in the access logs for letsencrypt but not sure why the remote end is getting timeouts.

one another example:
https://acme-v02.api.letsencrypt.org/acme/authz-v3/39962305980

[rg305]

Hi @Maxwell and welcome to the LE community forum

@Maxwell

Timeout during connect (likely firewall problem)

This usually means that port 80 is blocked.
Something is preventing the HTTP challenge request to your site from being reached.
You must have a working HTTP site before it can be secured (via HTTP validation).

[Maxwell]

@rg305 Thank you so much!
Yes that was my first thought as well.
But The port 80 and 443 are open for the world. The server is hosting other sites as well and their renewal were completed. And we are able to access the same validation URL from other online tools as well. Also we are seeing 200 status code in the access logs for the same validation URLs.

So was looking for more insight.

[rg305]

Maybe you are blocking part of the Internet?
Geolocation blocking?