Sharepoint in SQL AGL intermittent timeout

Quote:
Intermittent, unusually high latency might occur when you use availability groups that have replicas that are deployed on multiple subnets.
As a best practice, connections to SharePoint availability groups in a multi-subnet environment should configure specifyMultiSubnetFailover=True to avoid issues caused by high network latency. For more information, see Supporting Availability Group Multi-Subnet Failovers.



Below should run in Sharepoint application server each time create / recreate sharepoint site to make sure multisubnetfailover keyword in add into sharepoint connection string

$dbs = Get-SPDatabase | ?{$_.MultiSubnetFailover -ne $true}
     foreach ($db in $dbs)
     {
          $db.MultiSubnetFailover = $true
           $db.Update()
     }

Reference :
Configure SQL Server 2012 AlwaysOn Availability Groups for SharePoint 2013