diff --git a/tests/infrastructure/default.nix b/tests/infrastructure/default.nix
index decc0da..d23febb 100644
--- a/tests/infrastructure/default.nix
+++ b/tests/infrastructure/default.nix
@@ -162,5 +162,8 @@
         client1.succeed("ssh ${sshOptions} seb@server 'echo Hello'")
         client1.succeed("ssh ${sshOptions} seb@client2 'echo Hello'")
         server.fail("ssh ${sshOptions} seb@client2 'echo Hello'")
+
+      with subtest("SSH not reachable on underlay"):
+        client1.fail("ssh ${sshOptions} seb@${serverNetCfg.underlay.address} 'echo Hello'")
     '';
 }