And I am having the exact same issue, having followed the exact same process. The device doesn’t allow me to connect to it via the hotspot either (connecting as private SSID, Windows and Mac both refuse to connect).
Have a look in the router if your spark actually gets an ip address assigned and try to ping it. Might be wild guess, but from the good old days it was always recommended not to use spaces in anything network related. With that in mind it might be worth to rename your network ssid.
Disconnect any QSFP cables and try again. I’ve found that cheap QSFP cables can disrupt WiFi enough to kill it, likely due to poor shielding. Especially in the port closest to the USB-C ports. I’ve had no WiFi issues using the approved QSFP cable.
I got the same issue on 2x Acer GN100s - Acer wants me to send them in for repair… I tried to restore from the only image they provide - DGXOS-Spark-Acer-20251204-repack-GA1.2.1-OTA1.1-RC (same issue - wasn’t expecting anything different tbh). What’s the risk of using the NVIDIA recovery image?