Warning: One or more devices cannot connect to the Sophos Mobile server. Cannot find affected phone.

Hello,

I did an update to SMC 9 and we recently renewed our license.

Now we get alot of emails like this:
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Warning: One or more devices cannot connect to the Sophos Mobile server (mobilecontrol.vandorp.eu) because the server certificate is classified as untrusted. Verify that the configured list of SSL certificates is up to date.
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When I look in the server.log, I got some errors like this one:
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2019-09-26 14:33:15,168 ERROR [com.sophos.mobilecontrol.server.worker.maintenance.MDMAppDeviceTriggerTimer] (EJB default - 10) could not trigger android smc app on Device [deviceId=20371, deviceGroupId=2, customerId=1, name=D**************l, email=n********@*********u, osId=20, lastSeenDate=2019-04-16 12:39:19.898,lastAppSyncDate=2019-04-16 12:39:19.898,deviceOwner=employee, modelName=Samsung Galaxy J3(2016), managedState=managed, managementType=FULL_MDM, compliant=true, easState=ALLOWED_BY_COMPLIANCE, nacState=ALLOWED_BY_COMPLIANCE, containerState=ALLOWED_BY_COMPLIANCE, complianceViolationSeverity=COMPLIANT, Base [tan=935, updateDate=2019-04-16 12:39:19.96, insertDate=2017-06-13 13:07:23.6, updatedby=s****m, insertedby=5**5]], trigger result is NOTIFICATION_FAILED
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We have 1700 entries in SMC
Can you tell me how I can find out which telephone this is?
Or can you tell me what I can do about these errors?