MuxIO NodeUnavailableException during rebalance

SDK: .NETCore

Environment:

• OS: Windows Server 2012 R2
• Mode : sync , muxio

Error: NodeUnavailable

Scenario: Restart all nodes

Issue : After restarting phase is done, all subdoc request failed with error 'NodeUnavailable'. This was due to https://github.com/couchbase/couchbase-net-client/blob/master/Src/Couchbase/IO/Services/MultiplexingIOService.cs#L334 throws following exceptions

System.Security.Authentication.AuthenticationException: Authentication failed for bucket 'default'
System.TimeoutException: The operation has timed out.

I'm not sure why those two exceptions but, later when the rebound phase is almost done, I see the log that is saying

Successfully connected and marking data node xxx.xxx.xxx.xxx:11210 as up.

Which seemed printed after collecting all test data.