If you are still using the stock firmware, here is the current reality:

Remember: Do these four things, and your H267A V10 will run like new.

Let’s assume you have downloaded the correct update.bin file from your ISP. Here is the to ensure success:

Since official support has ended, if your router is experiencing stability issues or security vulnerabilities, it is highly recommended to contact your ISP for a hardware replacement to a newer, supported model. before attempting any changes? A Journey to the Firmware of ZTE H267A: Part I - Kaan Basal

Based on community and ISP reports: