Wi-Fi security · Plain-English answer
Yes. A VPN works over 4G and 5G exactly as it does over Wi-Fi, encrypting traffic from your phone to the VPN server. It hides your browsing from your mobile carrier and gives apps and websites a different IP address. It uses your data allowance, plus a small amount of protocol overhead.
A VPN app does not care what carries its packets. Once connected over mobile data, the tunnel behaves identically to one over Wi-Fi: apps and websites see the VPN server's address, and the carrier sees only an encrypted stream to one destination. Modern protocols handle the switch between Wi-Fi and mobile data gracefully, reconnecting in moments as you leave the house.
The traffic still counts against your data allowance, with a few percent of encryption overhead on top, so the main practical consideration on small plans is volume rather than security.
The radio link between your phone and the mast is indeed encrypted, so mobile data does not need a VPN for the reason public Wi-Fi does. What the carrier encryption does not do is hide anything from the carrier itself, which can observe the sites you visit and often monetises that in aggregate.
A VPN closes that gap, keeps your IP address consistent for services that dislike changing addresses, and behaves identically as you roam between networks. ROOT keeps no activity logs, so shifting visibility from carrier to VPN is a genuine improvement rather than a swap.
ROOT VPN is free to start with unlimited data, no card needed, and no activity logs.
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