There is a problem with the proxy server's security certificate

I have 2 exchange 2013 server with all in one role with DAG configured. Getting attached error every 4 - 5 days once for all users and need to restart both server's. Then again it will work fine for some day. What might be the issue
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kolathaya123Author Commented:
Seth SimmonsSr. Systems AdministratorCommented:
run the exchange connectivity test for autodiscover and outlook anywhere

also see this article

Error message when Outlook tries to connect to a server by using an RPC connection or an HTTPS connection: "There is a problem with the proxy server's security certificate"
Can you check what authentication methods are used on outlook anywhere

Check with: Get-OutlookAnywhere | fl *auth*

Here's the default values:
ExternalClientAuthenticationMethod : Negotiate
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm, Negotiate}
kolathaya123Author Commented:
I installed SP1 and CU5, and till now it is fine

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