My router is on firmware RUT9XX_R_00.06.00.4. which does not have the Zerotier tab. When i upgrade from the file from your above link - (RUT9XX_R_44.05.04.4_WEBUI.bin) I get following error message:
"Firmware upgrade - verification failed
This device's provisioning doesn't allow it to be downgraded to a firmware version older than RUT9XX_R_00.06.00.
Ensure to get a correct firmware image and try to upgrade again.
Size: 11.75 MB (15.19 MB available)
Note: Uploaded firmware image version is older than current firmware version. All configuration files will be erased."
Is there another way to "downgrade" to the older version with zerotier support?