This is the simplest method, as the router handles the download and installation. TeamViewer How to update your router's firmware - TeamViewer
Connect to your router’s network (Wi-Fi or Ethernet) and log into the admin panel. You need to know your current build number before upgrading. Update Software in ZTE ZXHN H267N
This is the easiest method and does not require downloading files manually. This is the simplest method, as the router
Ensure your router is connected to a reliable power source; a power failure during the update can "brick" the device. How to Update Your ZTE ZXHN H267N This is the simplest method