Analysis: What is the best VPN for the mobile operating system ZenUI

Best VPN for ZenUI: A practical, slightly geeky guide

ZenUI is ASUS’s Android skin that’s both slick and occasionally overzealous with battery-saving and app management. If you use an ASUS phone or tablet running ZenUI and want a VPN that’s fast, private, and resilient to ZenUI’s tendency to send background apps to Siberian exile, you need more than “any old Android VPN.” You need a VPN that supports Android’s Always-on VPN, offers robust kill-switch behavior, plays nicely with aggressive battery optimizers, and ideally supports modern protocols like WireGuard for speed. Below I compare top contenders, explain ZenUI-specific gotchas, and recommend the best picks for different priorities.

Quick verdict

• Best overall: ExpressVPN — excellent Android app, rock-solid Always-on and kill switch, fast WireGuard-like protocol (Lightway), and great router support.
• Best privacy-first: Mullvad or Proton VPN — minimal logging, strong audit track records Mullvad is superb for privacy purists.
• Best value / unlimited devices: Surfshark — solid Android app, strong feature set, good price.
• Best for power users: OpenVPN/Router setup via ASUSWRT or Merlin with providers that allow manual configs (PIA, Nord, ExpressVPN) — use router-level VPN to protect everything without ZenUI fighting background services.

Comparison table

ZenUI-specific issues and fixes

ZenUI likes to optimize (i.e., kill) background apps to save battery. That’s usually good — until it terminates your VPN service and leaves you leaking DNS and traffic while thinking you’re protected. Two primary fixes:

1. Whitelist the VPN app from battery optimization / enable autostart. ZenUI has per-app optimization controls find your VPN and set it to Not optimized or Autostart so ZenUI leaves it alone.
2. Use Android’s Always-on VPN Block connections without VPN. This enforces a system-level kill switch that prevents network access unless the VPN is active. See Android’s documentation for dev-level details: https://developer.android.com/guide/topics/connectivity/vpn.

Pro tip for the terminally cautious: test for leaks while toggling ZenUI battery modes. A quick DNS leak test in your browser can tell you whether traffic is sticking to the tunnel.

Why protocol support matters on ZenUI

WireGuard (or WireGuard-based variants like NordLynx) offers excellent speed and efficiency, which is helpful on mobile where CPU and battery matter. ExpressVPN’s Lightway is similar in spirit — designed for mobile reliability and fast reconnection after a network change (important when switching from Wi‑Fi to mobile data). Classic OpenVPN is solid and widely supported (useful for manual router configs), but it’s heavier on battery and CPU.

Learn more about modern VPN protocols: https://www.wireguard.com/ and https://openvpn.net/.

Router vs. device VPN

If ZenUI keeps fighting you (or you want every device on your ASUS router protected without installing an app), consider configuring VPN on the router. ASUSWRT and ASUSWRT‑Merlin support client modes for OpenVPN and WireGuard (with varying provider support). Running the VPN at the router level removes the need to wrestle with ZenUI’s app lifecycle. See the Merlin project for advanced router firmware info: https://www.asuswrt-merlin.net/.

Privacy logging — what to check

ZenUI is a skin the real privacy question is the VPN’s policy and jurisdiction. Look for audited no-log policies and transparency reports. Mullvad, Proton, and ExpressVPN have strong reputations and independent audits to back their claims. If you care about real-world resistance to subpoenas, check provider jurisdiction and whether they’ve been audited or subpoenaed before.

Recommendations (practical)

• Best overall (recommended): ExpressVPN — if you want a hassle-free, fast, and reliable experience. ExpressVPN’s Lightway reconnects fast during mobile handovers and it has excellent Android UX. Good for streaming, privacy, and those who don’t want to tweak ZenUI settings constantly. ExpressVPN.
• Best for privacy nerds: Mullvad or Proton VPN — Mullvad’s anonymous account model and simplicity are a dream if you want minimum data shared Proton brings a strong privacy brand and a good Android app. Mullvad and Proton VPN.
• Best value / unlimited devices: Surfshark — excellent for households with many devices. It’s budget-friendly and feature-packed. Surfshark.
• For router-centric protection: Pick a provider that publishes manual configs for OpenVPN/WireGuard (ExpressVPN, Nord, PIA, etc.) and set the VPN on your ASUS router to avoid ZenUI interference.

Quick setup checklist for ZenUI

• Install chosen VPN from Google Play or provider APK.
• Open ZenUI Settings → Apps → Battery optimization (or Auto Start) and whitelist the VPN.
• Enable Android Always-on VPN in Settings → Network → VPN (select VPN and toggle Always-on also toggle “Block connections without VPN”).
• Test for DNS and IP leaks via an online leak test while toggling Wi‑Fi and mobile data.
• Optional: Configure VPN on your ASUS router for blanket protection.

Sources and further reading

• Android VPN developer guide: https://developer.android.com/guide/topics/connectivity/vpn
• ExpressVPN Android app: https://www.expressvpn.com/apps/android
• NordVPN Android: https://nordvpn.com/download/android/
• Surfshark Android: https://surfshark.com/download/android
• Proton VPN Android: https://proton.me/vpn/download/android
• Mullvad Android: https://mullvad.net/en/download/android/
• WireGuard: https://www.wireguard.com/ OpenVPN: https://openvpn.net/
• ASUSWRT‑Merlin (router firmware): https://www.asuswrt-merlin.net/
• ZenUI (background info): https://en.wikipedia.org/wiki/ZenUI

In short: pick a provider with a strong Android app and modern protocol support, whitelist it in ZenUI, enable Always‑on and “block without VPN,” and test. If ZenUI still behaves like a jealous roommate, move the VPN to the router — then everything on your network is protected and ZenUI can sulk alone.