At least some configuration info might be in order. Kaspersky doesn’t complain about my certs at all… However when accessing my sites and inspecting the cert(s) it says “verified by Kaspersky” not Lets Encrypt… All of the other info is correct. Valid dates etc… When accessing from a variety of other workstations without Kaspersky installed the inspection behavior is normal…
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Is Kaspersky installed on the server, or a workstation that is accessing the server?
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Please consider dumping TLSv1 support and use the following guide to strengthen your cipher suite
https://mozilla.github.io/server-side-tls/ssl-config-generator/
And as @schoen states, verify your domain isn’t on a blacklist (always a good idea) 
This is what Kaspersky shows me…
Rip