N1QL queries started failing after restart the server

We have more than 20+ servers in the CB cluster.
For one server facing some issues so it is restated but after that N1QL queries started failing on remaining 20+ servers. IIUC, in case of one server down, other servers in the cluster serve the traffic but n1QL queries failed on other server.
Why the N1QL queries failing on the other servers as well?
I would like to know your opinion.

The data resides on all data nodes. The down server has data node and you don’t have replica, auto switch is not enabled, N1QL queries will fail if it accessing down data node.

Thank you for your reply @vsr1

we are using Couchbase server 5.1.
The N1QL query is failing even after recovery and rebalance is done.
The N1QL queries were working fine on the recovered node but not working on other nodes. The timeout exception occured on other nodes.
After restarting all other nodes the N1QL works fine.

Is there any bug in Couchbase server 5.1?
Thanks in advance.