diff --git a/05-single-hop-route/test_spec05.py b/05-single-hop-route/test_spec05.py
index 3211afc..b387f25 100644
--- a/05-single-hop-route/test_spec05.py
+++ b/05-single-hop-route/test_spec05.py
@@ -1,10 +1,17 @@
 import pytest
+import random
 
 from riotctrl_shell.gnrc import GNRCICMPv6Echo, GNRCIPv6NIB, GNRCPktbufStats
 from riotctrl_shell.netif import Ifconfig
 
 from testutils.native import bridged
-from testutils.shell import ping6, lladdr, check_pktbuf
+from testutils.shell import (
+    ping6,
+    lladdr,
+    check_pktbuf,
+    has_global_addr,
+    try_to_remove_global_addr,
+)
 
 
 APP = 'examples/gnrc_networking'
@@ -42,26 +49,36 @@ def test_task01(riot_ctrl):
     check_pktbuf(pinged, pinger)
 
 
-@pytest.mark.flaky(reruns=3, reruns_delay=30)
+@pytest.mark.flaky(reruns=0, reruns_delay=30)
 @pytest.mark.iotlab_creds
 @pytest.mark.parametrize(
     'nodes', [pytest.param(['iotlab-m3', 'iotlab-m3'])], indirect=['nodes']
 )
 def test_task02(riot_ctrl):
     pinger, pinged = (
-        riot_ctrl(0, APP, Shell, modules=["shell_cmd_gnrc_pktbuf"]),
-        riot_ctrl(1, APP, Shell, modules=["shell_cmd_gnrc_pktbuf"]),
+        riot_ctrl(0, APP, Shell, modules=["shell_cmd_gnrc_pktbuf"], cflags="-DCONFIG_IEEE802154_DEFAULT_CHANNEL=13"),
+        riot_ctrl(1, APP, Shell, modules=["shell_cmd_gnrc_pktbuf"], cflags="-DCONFIG_IEEE802154_DEFAULT_CHANNEL=13"),
     )
 
     pinged_netif, pinged_lladdr = lladdr(pinged.ifconfig_list())
-    pinged.ifconfig_add(pinged_netif, "beef::1/64")
     pinger_netif, pinger_lladdr = lladdr(pinger.ifconfig_list())
+
+    if has_global_addr(pinged) or has_global_addr(pinger):
+        pan_id = format(random.randint(0x1000, 0xFFFF), "x")
+        pinged.ifconfig_set(pinged_netif, "pan_id", pan_id)
+        pinger.ifconfig_set(pinger_netif, "pan_id", pan_id)
+        pinged.ifconfig_set(pinged_netif, "chan", "12")
+        pinger.ifconfig_set(pinger_netif, "chan", "12")
+        try_to_remove_global_addr(pinged)
+        try_to_remove_global_addr(pinger)
+
+    pinged.ifconfig_add(pinged_netif, "beef::1/64")
     pinger.ifconfig_add(pinger_netif, "affe::1/120")
 
     pinged.nib_route_add(pinged_netif, "::", pinger_lladdr)
     pinger.nib_route_add(pinger_netif, "::", pinged_lladdr)
 
-    res = ping6(pinger, "beef::1", count=100, interval=300, packet_size=1024)
+    res = ping6(pinger, f"beef::1", count=100, interval=300, packet_size=1024)
     assert res['stats']['packet_loss'] < 10
 
     check_pktbuf(pinged, pinger)
diff --git a/testutils/github.py b/testutils/github.py
index d59761c..7d95fc2 100644
--- a/testutils/github.py
+++ b/testutils/github.py
@@ -210,9 +210,9 @@ def create_comment(github, issue):
 def _generate_outcome_summary(pytest_report, task):
     # pylint: disable=C0209
     return "<strong>{a_open}{outcome}{a_close}</strong>".format(
-        a_open='<a href="{}">'.format(task["outcome_url"])
-        if "outcome_url" in task
-        else '',
+        a_open=(
+            '<a href="{}">'.format(task["outcome_url"]) if "outcome_url" in task else ''
+        ),
         outcome=pytest_report.outcome.upper(),
         a_close='</a>' if "outcome_url" in task else '',
     )
diff --git a/testutils/iotlab.py b/testutils/iotlab.py
index 49d5fdd..8f89317 100644
--- a/testutils/iotlab.py
+++ b/testutils/iotlab.py
@@ -1,4 +1,5 @@
 import logging
+import random
 import re
 
 from iotlabcli.auth import get_user_credentials
@@ -55,14 +56,14 @@ def __init__(self, name, ctrls, site=DEFAULT_SITE):
     def board_from_iotlab_node(iotlab_node):
         """Return BOARD matching iotlab_node"""
         reg = r'([0-9a-zA-Z\-]+)-\d+\.[a-z]+\.iot-lab\.info'
-        match = re.search(reg, iotlab_node)
-        if match is None:
+        matches = re.findall(reg, iotlab_node)
+        if not matches:
             raise ValueError(
                 f"Unable to parse {iotlab_node} as IoT-LAB node "
                 "name of format "
                 "<node-name>.<site-name>.iot-lab.info"
             )
-        iotlab_node_name = match.group(1)
+        iotlab_node_name = random.choice(matches)
         dict_values = IoTLABExperiment.BOARD_ARCHI_MAP.values()
         dict_names = [value['name'] for value in dict_values]
         dict_keys = list(IoTLABExperiment.BOARD_ARCHI_MAP.keys())
diff --git a/testutils/shell.py b/testutils/shell.py
index 0aaeee7..e70ca59 100644
--- a/testutils/shell.py
+++ b/testutils/shell.py
@@ -222,6 +222,22 @@ def global_addr(ifconfig_out):
     return first_netif_and_addr_by_scope(ifconfig_out, "global")
 
 
+def has_global_addr(node):
+    """Check if node has a global address."""
+    try:
+        global_addr(node.ifconfig_list())
+    except (RuntimeError, IndexError):
+        return False
+    return True
+
+
+def try_to_remove_global_addr(node):
+    """Try to remove global address from node."""
+    if has_global_addr(node):
+        netif, addr = global_addr(node.ifconfig_list())
+        node.cmd(f"ifconfig {netif} del {addr}")
+
+
 def check_pktbuf(*nodes, wait=10):
     if wait:
         time.sleep(wait)
diff --git a/testutils/tests/test_github.py b/testutils/tests/test_github.py
index 824abe2..e3930b3 100644
--- a/testutils/tests/test_github.py
+++ b/testutils/tests/test_github.py
@@ -983,9 +983,11 @@ def test_upload_results(
     monkeypatch.setattr(
         testutils.github,
         "get_results_gist",
-        lambda *args, **kwargs: (testutils.github.Git('.'), "", "the_gist_id")
-        if gist_created
-        else (None, None, None),
+        lambda *args, **kwargs: (
+            (testutils.github.Git('.'), "", "the_gist_id")
+            if gist_created
+            else (None, None, None)
+        ),
     )
     monkeypatch.setattr(
         testutils.github, "upload_result_content", lambda *args, **kwargs: head