Error performing queries against < 6.5

Seeing an error from the SDK under this Query scenario: 

Operations: Continuous stores and queries (prepared queries)

Change: Fail over node 2, and rebalance it out

Cluster: (6.0.3)

1. kv
2. n1ql 
3. index
4. n1ql

Error: Seeing this error continuously during the run, and the test hangs at the end

09:08:36 [77.11 INFO] (SDKD log:137) Scheduling query returned error 0xd6 LCB_ERR_UNSUPPORTED_OPERATION (214)
09:08:36 [77.11 INFO] (SDKD log:137) Inserting document returned error 0x3f2 LCB_ERR_NO_MATCHING_SERVER (1010)

(from https://github.com/couchbase/sdkd-cpp/blob/master/src/N1QLQueryExecutor.cpp#L103)

And internally I spotted what may be the cause?:

09:25:45 [73.93 INFO] (SDKD log:137) 41ms ERROR [I224e81fd7333a0f] (negotiation - L:157) <172.23.109.21:11210> (CTX=0x7f7698015750,sasl,SASLREQ=0x7f7698015b30) Error: 0x41a, Other auth error 

Logs: sdkd-cpp_log.txt.zip

Note, that when the cluster is set up like this:

1. kv
2. kv,index,fts,n1ql
3. kv,index,fts,n1ql
4. kv,index,fts,n1ql

The test passes.