.NETCore SDK throws Failed to acquire a pooled client connection on xxx.xxx.xxx.xxx:11210 after 5 tries.

.NETCore SDK on Windows with muxio and async mode throws exception "Failed to acquire a pooled client connection on xxx.xxx.xxx.xxx:11210 after 5 tries. " while UpsertAsync(https://github.com/couchbase/couchbase-net-client/blob/master/Src/Couchbase/CouchbaseBucket.cs#L3401) is called, which in turn calls SendWithDurabilityAsync(https://github.com/couchbase/couchbase-net-client/blob/master/Src/Couchbase/Core/Buckets/CouchbaseRequestExecuter.cs#L331) and SendWithDurabilityAsync returns OperationResult type with OperationResult.Exception assigned with the exception.