diff --git a/test/TEST-21-DFUZZER/test.sh b/test/TEST-21-DFUZZER/test.sh
index 7669e4e0ad..eb0a6549e0 100755
--- a/test/TEST-21-DFUZZER/test.sh
+++ b/test/TEST-21-DFUZZER/test.sh
@@ -3,7 +3,6 @@
 set -e
 
 TEST_DESCRIPTION="Fuzz our D-Bus interfaces with dfuzzer"
-TEST_NO_NSPAWN=1
 TEST_SUPPORTING_SERVICES_SHOULD_BE_MASKED=0
 QEMU_TIMEOUT="${QEMU_TIMEOUT:-1800}"
 IMAGE_NAME=dfuzzer
@@ -12,6 +11,13 @@ TEST_FORCE_NEWIMAGE=1
 # shellcheck source=test/test-functions
 . "${TEST_BASE_DIR:?}/test-functions"
 
+# Run the test either only under nspawn (if $TEST_PREFER_NSPAWN is set to true)
+# or only uder qemu otherwise, to avoid running the test twice on machines where
+# we can do both.
+if ! get_bool "${TEST_PREFER_NSPAWN:=}"; then
+    TEST_NO_NSPAWN=1
+fi
+
 command -v dfuzzer >/dev/null || exit 0
 
 if ! get_bool "$IS_BUILT_WITH_ASAN"; then
diff --git a/test/units/testsuite-21.sh b/test/units/testsuite-21.sh
index e9bf18603a..d931e63167 100755
--- a/test/units/testsuite-21.sh
+++ b/test/units/testsuite-21.sh
@@ -15,7 +15,7 @@ at_exit() {
     # from the queue
     if [[ $SHUTDOWN_AT_EXIT -ne 0 ]] && ! systemctl poweroff; then
         # PID1 is down let's try to save the journal
-        journalctl --sync || : # journal can be down as well so let's ignore exit codes here
+        journalctl --sync      # journal can be down as well so let's ignore exit codes here
         systemctl -ff poweroff # sync() and reboot(RB_POWER_OFF)
     fi
 }
@@ -33,17 +33,31 @@ BUS_LIST=(
     org.freedesktop.locale1
     org.freedesktop.login1
     org.freedesktop.machine1
-    org.freedesktop.network1
     org.freedesktop.portable1
     org.freedesktop.resolve1
     org.freedesktop.systemd1
     org.freedesktop.timedate1
-    org.freedesktop.timesync1
 )
 
 # systemd-oomd requires PSI
 if tail -n +1 /proc/pressure/{cpu,io,memory}; then
-    BUS_LIST+=(org.freedesktop.oom1)
+    BUS_LIST+=(
+        org.freedesktop.oom1
+    )
+fi
+
+# Some services require specific conditions:
+#   - systemd-timesyncd can't run in a container
+#   - systemd-networkd can run in a container if it has CAP_NET_ADMIN capability
+if ! systemd-detect-virt --container; then
+    BUS_LIST+=(
+        org.freedesktop.network1
+        org.freedesktop.timesync1
+    )
+elif busctl introspect org.freedesktop.network1 / &>/dev/null; then
+    BUS_LIST+=(
+        org.freedesktop.network1
+    )
 fi
 
 SESSION_BUS_LIST=(