Merge "Speculatively fix L2TP keepalive issues by reducing mtu" am: 392b52f49f am: 926d1ee880

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1399646

Change-Id: Ie6a7fdb8e1ce035ce145b90645290e7e4777f7e6