diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -272,8 +272,9 @@
 
 # The maximum number of nodes a single test can spawn
 MAX_NODES = 12
-# Don't assign rpc or p2p ports lower than this
-PORT_MIN = int(os.getenv('TEST_RUNNER_PORT_MIN', default=11000))
+# Don't assign rpc or p2p ports lower than this (for example: 18333 is the
+# default testnet port)
+PORT_MIN = int(os.getenv('TEST_RUNNER_PORT_MIN', default=20000))
 # The number of ports to "reserve" for p2p and rpc, each
 PORT_RANGE = 5000