Dell Unity: Replication Session must be in a start or ok state before it can be synced. (Error Code:0x650010a)

The replication is not running and showing an error message:

The connection with this remote replication host has been lost. On the Replication Connections page, click the Verify and Update Connection button.

Running 'Verify and Update' on the connection Succeeds from both Source and Destination arrays but Replication sessions continue to show 'connection lost'.

Pinging is successful from both source and destination arrays.

In this specific case, the network connection between sites was switched to a DR network and the MTU settings were not set to Jumbo Frames for all network devices. The incorrect MTU settings caused large frames to be dropped leading to the 'connection lost' messages.

Similarly to the below KBA, either reconfigure MTU to 1500 or setup 9000 MTU across the entire network (network admin):
Unity: Asynchronous Remote Replication hung at "Creating Replication Session" (User Correctable)

During creating asynchronous remote replication session on a NAS server or LUN, the job stops responding at the step of "creating replication session" and does not get completed to ... 83%). 1- Ports 8888 and 5085 must be opened for the replication on the firewall and also with Unity MGMT IP. ... 2- Jumbo Frame configuration on network. ...

March 12, 2017 | Approved | Level 30 = Customers | 496612 | Dell EMC Unity Family