Up until 1.20, k3s shipped with Traefik 1.7.x built in. Since 1.21, Traefik 2.4.x has been the bundled version. If you upgraded your k3s deployment from <=1.20 to >=1.21 k3s will do nothing if it detects Traefik 1 installed. So it’s up to the adminstrator to upgrade it. Here’s how I did it in my cluster with some basic examples.