Queries are very slow after replacing the client machine

[A J V PRASAD]

We have replaced a client PC which has a read-only access to a MySql Enterprise server - advanced addition ( commercial ) version 5.5.18 running on RHEL 5.4.

After that there is a severe slowness in execution of queries( in other terms getting the results). A query giving result in 1 second earlier is now taking 15 minutes. Query has multiple joins but on indexed keys only.

Details:

1) There is no change in the server in any respect.

2) Client and server are in the same physical LAN.

3) Previous client machine is running on RHEL 5.9 with stock mysql client.

4) New client machine is running on RHEL 7.4 and client is from mariadb ( stock).

5) To rule out any compatibility issue, downloaded the mysql 5.7.28 source and compiled everything and used the client from it, but the same issue.

6) removed the DNS configuration in new client machine and checked but the same issue.

7) There is no doubt on network as new client machine is connected to same port from which old client is removed.

8) To recheck, the old client machine is connected back and everything is fine.

9) Networking is through IPv4.

Please throw some light on the possible issues.

Thanks.