diff --git a/test/functional/p2p_disconnect_ban.py b/test/functional/p2p_disconnect_ban.py
--- a/test/functional/p2p_disconnect_ban.py
+++ b/test/functional/p2p_disconnect_ban.py
@@ -9,6 +9,7 @@
 from test_framework.util import (
     assert_equal,
     assert_raises_rpc_error,
+    connect_nodes,
     connect_nodes_bi,
     wait_until,
 )
@@ -19,6 +20,10 @@
         self.num_nodes = 2
 
     def run_test(self):
+        self.log.info("Connect nodes both way")
+        connect_nodes(self.nodes[0], self.nodes[1])
+        connect_nodes(self.nodes[1], self.nodes[0])
+
         self.log.info("Test setban and listbanned RPCs")
 
         self.log.info("setban: successfully ban single IP address")
@@ -85,7 +90,9 @@
 
         # Clear ban lists
         self.nodes[1].clearbanned()
-        connect_nodes_bi(self.nodes[0], self.nodes[1])
+        self.log.info("Connect nodes both way")
+        connect_nodes(self.nodes[0], self.nodes[1])
+        connect_nodes(self.nodes[1], self.nodes[0])
 
         self.log.info("Test disconnectnode RPCs")
 
diff --git a/test/functional/p2p_tx_download.py b/test/functional/p2p_tx_download.py
--- a/test/functional/p2p_tx_download.py
+++ b/test/functional/p2p_tx_download.py
@@ -126,6 +126,7 @@
         #   peer, plus
         # * the first time it is re-requested from the outbound peer, plus
         # * 2 seconds to avoid races
+        assert self.nodes[1].getpeerinfo()[0]['inbound'] is False
         timeout = 2 + (MAX_GETDATA_RANDOM_DELAY + INBOUND_PEER_TX_DELAY) + (
             GETDATA_TX_INTERVAL + MAX_GETDATA_RANDOM_DELAY)
         self.log.info(
diff --git a/test/functional/rpc_net.py b/test/functional/rpc_net.py
--- a/test/functional/rpc_net.py
+++ b/test/functional/rpc_net.py
@@ -15,7 +15,7 @@
     assert_greater_than_or_equal,
     assert_greater_than,
     assert_raises_rpc_error,
-    connect_nodes_bi,
+    connect_nodes,
     p2p_port,
     wait_until,
 )
@@ -31,6 +31,10 @@
                            ["-minrelaytxfee=0.00000500"]]
 
     def run_test(self):
+        self.log.info('Connect nodes both way')
+        connect_nodes(self.nodes[0], self.nodes[1])
+        connect_nodes(self.nodes[1], self.nodes[0])
+
         self._test_connection_count()
         self._test_getnettotals()
         self._test_getnetworkinginfo()
@@ -95,7 +99,10 @@
                    'connections'] == 0, timeout=3)
 
         self.nodes[0].setnetworkactive(state=True)
-        connect_nodes_bi(self.nodes[0], self.nodes[1])
+        self.log.info('Connect nodes both way')
+        connect_nodes(self.nodes[0], self.nodes[1])
+        connect_nodes(self.nodes[1], self.nodes[0])
+
         assert_equal(self.nodes[0].getnetworkinfo()['networkactive'], True)
         assert_equal(self.nodes[0].getnetworkinfo()['connections'], 2)
 
diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -22,6 +22,7 @@
 from .util import (
     assert_equal,
     check_json_precision,
+    connect_nodes,
     connect_nodes_bi,
     disconnect_nodes,
     get_datadir_path,
@@ -265,8 +266,18 @@
         # Connect the nodes as a "chain".  This allows us
         # to split the network between nodes 1 and 2 to get
         # two halves that can work on competing chains.
+        #
+        # Topology looks like this:
+        # node0 <-- node1 <-- node2 <-- node3
+        #
+        # If all nodes are in IBD (clean chain from genesis), node0 is assumed to be the source of blocks (miner). To
+        # ensure block propagation, all nodes will establish outgoing connections toward node0.
+        # See fPreferredDownload in net_processing.
+        #
+        # If further outbound connections are needed, they can be added at the beginning of the test with e.g.
+        # connect_nodes(self.nodes[1], 2)
         for i in range(self.num_nodes - 1):
-            connect_nodes_bi(self.nodes[i], self.nodes[i + 1])
+            connect_nodes(self.nodes[i + 1], self.nodes[i])
         self.sync_all()
 
     def setup_nodes(self):
diff --git a/test/functional/wallet_listsinceblock.py b/test/functional/wallet_listsinceblock.py
--- a/test/functional/wallet_listsinceblock.py
+++ b/test/functional/wallet_listsinceblock.py
@@ -4,10 +4,15 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the listsincelast RPC."""
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal, assert_array_result, assert_raises_rpc_error
+from test_framework.util import (
+    assert_array_result,
+    assert_equal,
+    assert_raises_rpc_error,
+    connect_nodes,
+)
 
 
-class ListSinceBlockTest (BitcoinTestFramework):
+class ListSinceBlockTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 4
         self.setup_clean_chain = True
@@ -17,6 +22,9 @@
         self.skip_if_no_wallet()
 
     def run_test(self):
+        # All nodes are in IBD from genesis, so they'll need the miner (node2) to be an outbound connection, or have
+        # only one connection. (See fPreferredDownload in net_processing)
+        connect_nodes(self.nodes[1], self.nodes[2])
         self.nodes[2].generate(101)
         self.sync_all()