Network coordinators do not make this magically happen. It’s just a dongle connected by network. When ZHA or Z2M (homeassistant is down) the coordinator has nothing to connect to and therefore zigbee is down.
You use a network coordinator to get the antenna away from the gear to get you a cleaner signal in a more central location of your install.
Suggest reading the cookbook section on zigbee The Home Assistant Cookbook - Index