Slave controller cannot connect to master after configuring SSL on EAP 7 domain

Issue

• We added ssl to our domain and now the slave cannot connect to the master. The slave connection times out:

2021-09-10 13:45:07,646 WARN  [org.jboss.as.host.controller] (Controller Boot Thread) WFLYHC0001: Could not connect to remote domain controller remote://ipaddress:9990: java.net.ConnectException: WFLYPRT0023: Could not connect to remote://ipaddress:9990. The connection timed out
    at org.jboss.as.protocol.ProtocolConnectionUtils.connectSync(ProtocolConnectionUtils.java:135)
    at org.jboss.as.host.controller.RemoteDomainConnection.lambda$openConnection$0(RemoteDomainConnection.java:223)
    at org.wildfly.common.context.Contextual.runExceptionAction(Contextual.java:108)
    at org.wildfly.security.auth.client.AuthenticationContext.run(AuthenticationContext.java:273)
    at org.jboss.as.host.controller.RemoteDomainConnection.openConnection(RemoteDomainConnection.java:223)
    at org.jboss.as.host.controller.RemoteDomainConnection$InitialConnectTask.connect(RemoteDomainConnection.java:594)
    at org.jboss.as.protocol.ProtocolConnectionManager.connect(ProtocolConnectionManager.java:70)
    at org.jboss.as.host.controller.RemoteDomainConnection.connect(RemoteDomainConnection.java:147)
    at org.jboss.as.host.controller.RemoteDomainConnectionService.register(RemoteDomainConnectionService.java:288)
    at org.jboss.as.host.controller.DomainModelControllerService.connectToDomainMaster(DomainModelControllerService.java:1010)
    at org.jboss.as.host.controller.DomainModelControllerService.boot(DomainModelControllerService.java:721)
    at org.jboss.as.controller.AbstractControllerService$1.run(AbstractControllerService.java:416)
    at java.lang.Thread.run(Thread.java:748)

• The master logs this IOException at that time

[Host Controller] ^[[32m^[[0m^[[32m13:45:37,665 DEBUG [io.undertow.request] (management I/O-1) UT005013: An IOException occurred: java.nio.channels.ClosedChannelException^[[0m
[Host Controller] ^[[32m        at io.undertow.protocols.ssl.SslConduit.doWrap(SslConduit.java:900)^[[0m
[Host Controller] ^[[32m        at io.undertow.protocols.ssl.SslConduit.doHandshake(SslConduit.java:673)^[[0m
[Host Controller] ^[[32m        at io.undertow.protocols.ssl.SslConduit.access$900(SslConduit.java:70)^[[0m
[Host Controller] ^[[32m        at io.undertow.protocols.ssl.SslConduit$SslReadReadyHandler.readReady(SslConduit.java:1215)^[[0m
[Host Controller] ^[[32m        at org.xnio.nio.NioSocketConduit.handleReady(NioSocketConduit.java:89)^[[0m
[Host Controller] ^[[32m        at org.xnio.nio.WorkerThread.run(WorkerThread.java:591)^[[0m