Security experts will scream that firmware updates are vital for patching vulnerabilities (like the infamous VPN bypass flaws in ZTE routers from 2020). And they are right. However, for an ISP-locked ZXHN H267A v10, your security update path is not a link—it is a phone call.
Before updating, check if you are already on the latest version. Connect your computer to the router via Ethernet cable. zxhn h267a v10 firmware update link
If you have a compatible firmware file, the general process for ZTE routers is: Security experts will scream that firmware updates are