Only set default port if there's an extIp or a dns4 domain

tests/testlib/wakunode.nim

@@ -24,7 +24,7 @@ proc newTestWakuNode*(nodeKey: crypto.PrivateKey,
                       bindIp: ValidIpAddress,
                       bindPort: Port,
                       extIp = none(ValidIpAddress),
-                      extPort = some(Port(60000)),
+                      extPort = none(Port),
                       extMultiAddrs = newSeq[MultiAddress](),
                       peerStorage: PeerStorage = nil,
                       maxConnections = builders.MaxConnections,
@@ -43,6 +43,13 @@ proc newTestWakuNode*(nodeKey: crypto.PrivateKey,
 
   var resolvedExtIp = extIp
 
+  # Update extPort to default value if it's missing and there's an extIp or a DNS domain 
+  let extPort = if (extIp.isSome() or dns4DomainName.isSome()) and
+                extPort.isNone():
+                some(Port(60000))
+              else:
+                extPort
+
   if dns4DomainName.isSome() and extIp.isNone():
     let conf = defaultTestWakuNodeConf()
     # If there's an error resolving the IP, an exception is thrown and test fails