A: Carrier variants sometimes took longer. Contact your carrier’s support. If they abandoned updates, unlock the bootloader (if possible) and flash the global firmware.
Vivo’s software update policy for mid-range phones at that time guaranteed only . The V5 launched with Marshmallow (6.0) and received Nougat (7.0). It never received Android 7.1.1 (Nougat MR1) or Android 8.0/8.1 Oreo. vivo v5 android version 7.0 update
A: Boot into recovery (Power + Volume Up), select "Wipe data/factory reset" and "Wipe cache partition." Then select "Reboot." You will lose data but the phone will boot into Marshmallow. Then try the OTA again after a fresh setup. A: Carrier variants sometimes took longer