I have no experience with CF, but for the kind of error you're getting you should check the cypher suite supported by CF and compare it with Webinoly. I know that CF have support for modern cypher suites in paid plans but is very rudimentary in free plans.
Webinoly only have support for modern cypher suites.
Although is not recommended, if you need change this settings, you can do it manually in /etc/nginx/nginx.conf
I don't know which cypher suite are supported by CF in their free plan.
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