IP address preset, PWM analog

Hi Everyone
How do I preset the device IP address in the source code ?
Only found SSID, the router connection, and password.
I would like to preset the IP address of the WLED, so I later on only have to change two digits.

PWM analog led is set 880Hz, do I only have to change it, where it says 880 ?
The meanwell LDD-L want 500Hz max, though they work with 2kHz, but no idea for how long.

Thank you

Why not just use DHCP reservations on your router?

Thought about that, but I would need to use the same router always.
I wanted to use an in stock router for testing and get a good outdoor router, when it works.
Maybe even a repeater/mesh system.

It is a test, whether I can use 80 - 100 WLEDs in the same network.

I have Ubiuiti EdgeRouter and UniFi with 36 WLED devices. Seems to work ok (about 90 wireless clients ATM).

I would never assign static IP unless it is a crucial server.