[{"data":1,"prerenderedAt":16},["ShallowReactive",2],{"blog-tag-en-mtu":3},[4],{"path":5,"title":6,"description":7,"date":8,"tags":9},"\u002Fblog\u002Fen\u002Fk3s-flannel-vxlan-overlay-mtu-troubleshooting","Ping Works, HTTP Hangs: Why K3s Flannel VXLAN Overlay Networks Break Over MTU","In a K3s cluster, ping succeeds but HTTP requests just hang — the culprit may be an MTU mismatch inside your VXLAN overlay network. This guide covers Flannel\u002FCalico MTU design, the PMTU blackhole phenomenon, and a step-by-step diagnostic process.","2026-09-01",[10,11,12,13,14,15],"k3s","kubernetes","networking","vxlan","flannel","mtu",1792488961755]