When you do a factory reset on the actiontec v.I router, does it also revert back to the old original firmware? If so, will it automatically update to the latest firmware.
No, the current firmware stays. Also, if there is a new firmware available at Verizon backend, the router will download it and automatically install it.
Furthermore, Actiontec MI424WR Rev. I is End of Life and End of Support back in September 2020, all rental units are given to the customers free of charge for recycling. I would advise you to recycle your Actiontec router because it no longer receives security updates and likely lacks necessary performance.