when you execute command
iperf -s on one system and
iperf -c x.x.x.x on another system. It comes out error "connect failed: No route to host" as follows.
Step 1: Display the status of firewalld
Step 2: Turn off firewalld
# systemctl stop firewalld.service
Step 3: Check the status of firewalld
# firewall-cmd --state