add coupler option for shielded cables

docs/network.md

@@ -20,7 +20,7 @@ There will be wired 100BASE-TX/1000BASE-T/10GBASE-T ethernet on the camping grou
 
 **Wired connections are completely unfiltered and will receive a public IP address**. If you have (older) devices that cannot be trusted with unrestricted incoming connections, bring a firewall. 
 
-You can lay your own ethernet cables (we don't provide them), but please do so in a tidy manner. You must not cross any roads, paths or borders between camping grounds. Always lay your cable from the Datenklo towards your tent to keep most of the slack close to your tent, but leave a few metres of slack cable at the Datenklo. Do not use shielded cables – these can damage equipment due to ground loops and we will not connect them.
+You can lay your own ethernet cables (we don't provide them), but please do so in a tidy manner. You must not cross any roads, paths or borders between camping grounds. Always lay your cable from the Datenklo towards your tent to keep most of the slack close to your tent, but leave a few metres of slack cable at the Datenklo. Do not use shielded cables – these can damage equipment due to ground loops and we will not connect them. As a remediation you can bring a RJ45 coupler (bonus points for plastic version) and a (short) unshielded cable. 
 
 The maximum distance to your nearest Datenklo will be approximately 50 meters, but bringing a longer cable is a good idea if you want to be sure. If your cable isn't long enough, you might find someone within range who has a switch and can plug you in.