diff --git a/Known-issues-and-solutions.md b/Known-issues-and-solutions.md
index 1162f88..146ba6a 100644
--- a/Known-issues-and-solutions.md
+++ b/Known-issues-and-solutions.md
@@ -1,4 +1,6 @@
-### Huge packet
+### Huge packet warning
+Upd2raw client and server communicates with raw socket, which doesn't support IP fragment. You you can't send packets larger than network MTU through udp2raw.  You need to make sure you set MTU parameters correctly at upper level application.
+
 Some times you will get "Huge packet" warnings even if you have set MTU correctly everywhere. It might be caused by the GRO feature of network drivers, you can try to add the `--fix-gro` on both sides to fix it.
 
 Related issue: