You generally cannot download firmware for the TP-Link VX420-G2h from the public TP-Link website because it is an ISP-customized device TP-Link Community
Before searching for a manual download, check if your router can update itself through its interface: TP-Link VX420-G2h Firmware Upgrades - TPG Group
You generally cannot download firmware for the TP-Link VX420-G2h from the public TP-Link website because it is an ISP-customized device TP-Link Community
Before searching for a manual download, check if your router can update itself through its interface: TP-Link VX420-G2h Firmware Upgrades - TPG Group vx420-g2h firmware download