One last update and, to document it in case some else has a similar issue. I believe we found the root cause of the failure. We have a Layer 7 Firewall policy that denies all Peer-to-Peer (P2P) traffic. Apparently 14.53 deals differently with that policy than 15.42. After many tests with the Meraki engineer we removed that specific policy and SAP started to work correctly. He (Meraki engineer) was checking at his captures and he stopped seeing the reset happening after the policy was removed. They are investigating what is causing that issue.    Thank you all for your help. ... View more