Do not download firmware packages from unverified forum links or random file-sharing platforms. Corrupted packages can destroy your router's flash memory.
New firmware often re-enables SIP ALG by default, which garbles voice calls. zxhn h267a v10 firmware update top
Most ISPs lock the bootloader on the H267A V10. You cannot flash generic ZTE firmware; you must flash the version. Do not download firmware packages from unverified forum