Free VPNs don't offer effective DPI bypassing, most don't have good speeds, and some are malicious. Cloudflare WARP is fast and non-malicious, but only provides WireGuard (easy to block).
** The protocol used is IKEv2 (fastest on unreliable links), or SoftEther (the best at bypassing DPI firewalls, with good speeds). +
*** NOTE: WireGuard is fastest on *not* unreliable links, but is easily detected by DPI firewalls.
*** If the speeds are lower than expected on all protocols, connect to the VPN on a different device, specifically one with link:https://en.wikipedia.org/wiki/AES_instruction_set#x86_architecture_processors[AES-NI supported].
. Ability to link:https://airvpn.org/faq/port_forwarding/[select ports to forward]; this heavily gauges if a VPN provider is good, even if you never need port forwarding.
WARNING: This guide can work regardless of root, but a rooted tethering device is recommended for additional control that is useful for increasing and/or maintaining speeds. +
Just ensure the rooted tethering device has no sensitive information, as root entirely breaks Android's security measures.
*1: link:https://topjohnwu.github.io/Magisk/[Install Magisk], then the link:https://github.com/Magisk-Modules-Repo/MagiskHidePropsConf#installation[MagiskHide Props Config] module.*
*2: Install the following apps; if needed, use the link:https://gitlab.com/AuroraOSS/AuroraStore/-/releases[Aurora Store] app for installing apps on the Google Play Store.*
** If using the official F-Droid app to download and install Termux, try using link:https://github.com/Iamlooker/Droid-ify/releases[Droid-ify] instead as the official app is unreliable.
* link:https://adguard-dns.com/en/public-dns.html[Configure AdGuard DNS manually] before using Network Signal Guru.
** link:https://github.com/AdAway/AdAway/releases[AdAway] is the alternative if you're not willing to change DNS servers, or using a paid VPN with no option to change the DNS servers used.
* link:https://play.google.com/store/apps/details?id=com.qtrun.QuickTest[Network Signal Guru for band locking], which can help maintain reliable speeds, and/or avoid congested bands for higher speeds.
For kernel tweakers: link:https://web.archive.org/web/20210423030541/https://forum.xda-developers.com/t/magisk-stock-bypass-tether-restrictions.4262265/[an example of enabling "xt_HL.ko" support through Magisk].
=== List of high-quality kernels with "xt_HL.ko" support, that also use the BBR TCP congestion control algorithm (which helps link:https://docs.google.com/spreadsheets/d/1I1NcVVbuC7aq4nGalYxMNz9pgS9OLKcFHssIBlj9xXI[maintain speeds over bad network conditions]):
* Compare the TTL and HL of the tethering (Android) device and any device connected to that router, they should both be the same TTL and HL. If not, change the increment (ttl-inc, hl-inc).
NOTE: For unlisted firmwares, if you get TTL & HL spoofing functional, please edit README.adoc to include instructions for that firmware, then make a Pull Request once you're done. +
As proof, provide a screenshot for each step of the new instructions.
=== Rooted tether device
* Show the currently used network interfaces; it's helpful for troubleshooting if needed.
*** Termux:Boot will automatically run set-tether-ttl.sh after startup/boot, though it will break if the interface name changes, which I cannot test nor know if this happens on Android, and if it does it may be specific to a ROM.
It'll make it easy to determine if this works, as after maxing the cap, some telecoms will use more tactics to ensure you're in line with how they want you to use their service.
* Use link:https://fast.com[Netflix's Speedtest]. This will test for throttling of streaming servers (Netflix), various forms of fingerprinting, and tethering/hotspot detections.
