How do I assign a static IP to my laptop that connects to my phone's hotspot?

Question

I'd like to assign a static IP address to my laptop when it connects to the mobile hotspot created by my Android 14 Xiaomi phone. This would allow me to access SFTP servers running on my laptop from my phone more easily. Additionally, it would be beneficial to have a static IP or a '.local' address for the phone itself, though setting a static IP for the laptop is my primary concern.

My laptop already has a .local address, but the address doesn't resolve in Android. (I thought this problem was solved in recent Android versions, but it still doesn't work.)

I can root the phone if needed.

Answer 1

Update: This does not work, as Android even randomizes the third part of the router IP, and uses a mask of 255.255.255.0.

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I used Hammerspoon to detect when I am connecting to the Wi-Fi of my phone, and then run this Zsh script to set the static IP automatically:

function ip-router {
    netstat -nr | perl -ne 'if (/^default\s+(\d+\.\d+\.\d+\.\d+)/) { print "$1\n"; exit }' | head -n1
}

local router_ip
router_ip="$(ip-router)"
if [[ "${router_ip}" =~ '^192\.168\.187\.' ]] ; then
    networksetup -setmanual Wi-Fi 192.168.187.7 255.255.0.0 "${router_ip}"

else
    echo "$0: router_ip does not match expected subnet."
fi