Lync or Skype for business deployment  with Enterprise pool including 3 or more frontends inside the pool

Users are unable to login to Lync client or the frontend services not starting sometimes, when checking the frontends logs you see a log of Event ID 32042 LS user services,

“Invalid incoming HTTPS certificate
Subject Name: xxx Issuer: xxx
Cause: this can happen if the HTTPS certificate has expired or is untrusted. The Certificate serial number is attached for reference….”

http://lyncdude.com/2015/12/05/ls-user-services-invalid-incoming-https-certificate/index.html