WFLYPRT0023: Could not connect to remote://10.111.10.123:9990. The connection timed out

I am using JBoss EAP 7.3 update 3.

RHEL 7.x 64-bit O/S

JBoss implementation in domain mode between two servers: master host lnx-08, slave host lnx-07

When starting the JBoss servers on the master server all servers start fine. No issues. When starting the Jboss servers on lnx-07 (slave) I receive the following error in the process-controller.log:
WFLYPRT0023: Could not connect to remote://10.111.10.123:9990. The connection timed out.

Here are the interface entries in the domain.xml:

10.111.10.123 is the ip for lnx-08.

As you can see I can ping lnx-08 from lnx-07 successfully:
[jboss@lnx-isat-shiv07 log]$ ping 10.101.10.123
PING 10.101.10.123 (10.111.10.123) 56(84) bytes of data.
64 bytes from 10.111.10.123: icmp_seq=1 ttl=64 time=0.462 ms
64 bytes from 10.111.10.123: icmp_seq=2 ttl=64 time=0.413 ms

And I can telnet over port 9990, but I do see an HTTP/1.1 400 Bad Request message:
[jboss@lnx-isat-07 log]$ telnet 10.101.10.123 9990

Trying 10.111.10.123...
Connected to 10.101.10.123.
Escape character is '^]'.
HTTP/1.1 400 Bad Request
Content-Length: 0
Connection: close
Connection closed by foreign host.

Firewall / port 9990 is open on lnx-07 (and lnx-08):
[root@lnx-isat-shiv07 ~]# firewall-cmd --list-all
public (active)
target: default
icmp-block-inversion: no
interfaces: ens161 ens192 ens224 ens256
sources:
services: dhcpv6-client ssh
ports: 7001/tcp 9990/tcp
protocols:
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:

And finally, as you can see, the Jboss servers on the master (lnx-08) are running:
[jboss@lnx-isat-shiv08 system]$ netstat -ln | grep ':9990 ' | grep 'LISTEN'
tcp 0 0 10.111.10.123:9990 0.0.0.0:* LISTEN

Any suggestions why this may be happening? This is a development env and was working until a reboot of the lnx-07 server. I dont have Linux support.

Thanks in advance
Andy