Try Pushbullet. I use it on my forum.
Link Preview Image GitHub - NodeBB-Community/nodebb-plugin-pushbullet: Allows NodeBB to interface with the Pushbullet service in order to provide push notifications to user mobile phonesAllows NodeBB to interface with the Pushbullet service in order to provide push notifications to user mobile phones - NodeBB-Community/nodebb-plugin-pushbullet
faviconGitHub (github.com)
Also search here for pushbullet, there are a number of threads for it.