From your description it sounds more like a problem with NLB or your network.

Hi,

Is there any error message when click Send/Receive All Folders? How about OWA during this problem arise?

Please run Test E-mail AutoConfiguration to return the result of the account configuration information, meanwhile check everything match the setting in Exchange server.
Firstly, run Test-ServiceHealth to list each Exchange role, what services are required for that role to function properly and which of those services are not running.
Run Test-OutlookConnectivity cmdlet to test end-to-end Microsoft Outlook client connectivity in the Microsoft Exchange Server 2010 organization. This includes testing for Outlook Anywhere (RPC/HTTP) and TCP-based connections.
More details about this command, please refer to: https://technet.microsoft.com/en-us/library/dd638082%28v=exchg.141%29.aspx?f=255&MSPPError=-2147217396

Thanks

Thanks for answering, I will perform these tests you mention me and I copied the results.

Something that is very rare is that it has already spent two days in a row at the same time, users are working properly all day, but after an hour the trouble begins, is when they come to eat and connect almost all at once .

You can be in this circumstance?

regards

You might want to start Performance Monitor to see if you're having CPU or disk performance problems.

Hi all, I have seen these events that appeared in the CAS servers

Log Name: System
Source: Schannel
Event ID:. 36888
Task Category: None
Level: Error
Keywords:
User: SYSTEM
Description:
10. The internal error state is 1203: The following unrecoverable alert was generated.


Log Name: System
Source: NETLOGON
Event ID:. 5816
Task Category: None
Level: Error
Keywords: Classic
User: Not available
Description:
Netlogon has been unable to make any request for authentication of the account in the domain NNNNNN YYYYY. It has timed out waiting for the request before it is sent to the domain controller in the domain \\ xxxxxxx YYYYY. This is the first mistake. If the problem persists, consolidated events are recorded every 30 minutes. See http://support.microsoft.com/kb/2654097 for more information.


and I have applied this KB in DCs

https://support.microsoft.com/en-us/kb/2654097?wa=wsignin1.0

After applying the Update, the problem persisted

I've also opened a case on the support of Microsoft and they told me to apply this KB in the CAS servers:

https://support.microsoft.com/en-us/kb/975363

It is to apply a patch (Fix287189) and then add in the CAS registry variable (MaxConcurrentApi) and set a value of 10.

The variable must be created on this route in the CAS:
HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ Netlogon \ Parameters

I restarted the CAS servers.


I HAVE TO WAIT A FEW DAYS BECAUSE This happened EVERY FEW HOURS



Regards