Expand maximum multiplayer limit
If you started a server the default player limit is 20 players. You can change this, but if you are only playing with a group of friends, 20 should be plenty.
This site explains how to download a server: http://www.howtogeek.com/202961/how-to-run-a-local-minecraft-pe-server-for-fun-and-persistent-world-building/
This site holds the download: http://www.pocketmine.net/
LAN does have its limitations and going around them is easiest.