I'm in the process of upgrading servers on a single domain. The old servers were physical 2008R2 servers with Exchange 2010 on the primary controller. The new servers are 2016 Standard VMs running on Hyper-V. Exchange is on one VM and the Domain Controller is on another VM with DHCP as well. There is an additional VM that is the backup Domain Controller. Since migrating to 2016 and decommissioning the 2010 server, the network workstations with Outlook (2010 to 2016) experience intermittent disconnects from Exchange Server 2016. There are 27 workstations on the network with another 10 connecting remotely and another 50 mobile devices that access the exchange email server. I've opened a Microsoft Support Ticket however they have not been able to resolve the issue in 3 weeks. We see error 26 in the client event log when the disconnect occurs however there is no other loss of connectivity across the network or internet. Typically we can resolve the issue by performing an ipconfig /release and ipconfig /renew however occasionally a reboot is required. DCDIAG is clean other than syslog errors. Replication is occurring without errors as well. Thanks for your help.