Install Tailscale on GL.iNET router, using microSD/USB storage.

tailscale-glinet.sh

#!/bin/bash

#
# Tailscale install script on GL.iNet devices
# Tested on BERYL (MT1300), should work on MANGO (GL-MT300N) 
# and probably other mipsel devices, as long as external storage (microSD/USB) 
# is available.
#
# Written by Thomas BOHL for Hemisphere-Project - 2022
# Free to use - No warranty provided
#
# Inspired by:
# https://bitsnbobs.kertho.me/en/posts/running-tailscale-on-a-mango-router/
# https://blog.patshead.com/2020/10/tailscale-on-my-gl-dot-inet-mango-openwrt-router.html
#

# exit when any command fails
set -e
trap 'last_command=$current_command; current_command=$BASH_COMMAND' DEBUG
trap 'echo "\"${last_command}\" command filed with exit code $?."' EXIT

# Hello
#
echo ".:: Tailscale on GL.iNet Beryl/Mango ::.\n"
echo "Install Tailscale on Beryl using microSD/USB storage.\n"
echo "NOTE: you must insert a microSD/USB before starting."
echo "WARNING: the microSD/USB will be completly ERASED ! (Ctrl-C to abort)"
read  -n 1 -p "= Press a key to continue or Ctrl-C to abort" D
echo "\n"

# Hostname
#
echo "Change device name" 
read  -p "= Hostname: " HOST_NAME
echo "\n"

if [[ ! -z "$HOST_NAME" ]]
then
    uci set system.@system[0].hostname="$HOST_NAME"
    uci commit system
    /etc/init.d/system reload
fi

# Version
#
echo "Enter current tailscale version, something like 1.22 (see https://pkgs.tailscale.com/stable/#static)" 
read  -p "= Version: " TS_VERSION
echo "\n"


# Install tools
#
opkg update
opkg install curl ca-bundle kmod-tun
opkg install kmod-usb-storage kmod-usb-storage-uas usbutils block-mount
opkg install gdisk e2fsprogs kmod-fs-ext4

# find microSD 
#
echo -n "Finding microSD... "
DEVPATH=""

if [ -b "/dev/sda" ]; then
    DEVPATH="/dev/sda"
    PARTPATH="/dev/sda1"
elif [ -b "/dev/mmcblk0" ]; then
    DEVPATH="/dev/mmcblk0"
    PARTPATH="/dev/mmcblk0p1"
else
    echo ""
    echo "ERROR: can't find microSD /dev path"
    #exit 1
fi
echo "$DEVPATH"

# format microSD
#
(
echo o # Remove all partitions
echo Y # confirm 
echo n # Add a new partition
echo   # First partition (Accept default: 1)
echo   # First sector (Accept default: 1)
echo   # Last sector (Accept default: varies)
echo   # HEX (Accept default: 8300)
echo w # Write changes
echo Y # confirm 
) | gdisk $DEVPATH 
(
echo y 
) | mkfs.ext4 $PARTPATH

# Automount
#
block umount
block detect | uci import fstab
uci set fstab.@mount[-1].enabled='1'
uci commit fstab
block mount

# Link opt
mkdir -p /mnt/mmcblk0p1/opt/tailscale/state
mkdir -p /mnt/mmcblk0p1/opt/tailscale/logs
ln -s /mnt/mmcblk0p1/opt /opt

# Download / Extract Tailscale
TAILSCA=tailscale_"$TS_VERSION"_mipsle
mkdir -p /opt/tailscale/archive
cd /opt/tailscale/archive
curl -O https://pkgs.tailscale.com/stable/"$TAILSCA".tgz
tar x -zvf "$TAILSCA".tgz
mv "$TAILSCA"/* /opt/tailscale/
ln -s /opt/tailscale/tailscale /usr/sbin/tailscale
ln -s /opt/tailscale/tailscaled /usr/sbin/tailscaled

# Startup script
echo "#!/bin/sh /etc/rc.common

USE_PROCD=1
START=80
STOP=01

start_service() {

    echo \"==== Starting tailscaled ====\"
    /usr/sbin/tailscaled --cleanup

    procd_open_instance
    procd_set_param command /usr/sbin/tailscaled
    procd_append_param command --port 41641
    procd_append_param command --state /opt/tailscale/state/tailscaled.state
    procd_set_param respawn
    procd_set_param stdout 1
    procd_set_param stderr 1
    procd_close_instance
}

stop_service() {
    echo \"==== Stop tailscaled ====\"
    /usr/sbin/tailscaled --cleanup
}
" > /etc/init.d/tailscale
chmod +x /etc/init.d/tailscale
/etc/init.d/tailscale enable
/etc/init.d/tailscale start

# Start tailscale
# tailscale up --advertise-routes=10.0.0.0/24
tailscale up

how to run this?
bash is not installed. changed to ash (delete debug-trap), but space is to low, to run the script itself...

I used it on a Beryl.
To get enough storage space, install it from/on the microSD storage as mentioned in the script comments.
Also make sure to read both link tutorials from the script comments.

Note that i recently bought a Beryl AX (wifi 6), and tailscale is now natively embedded in the Gl.inet OS !