I was assuming your server and Linux device were plugged in via Ethernet and your mobile devices were using WiFi. Now it sounds like your Linux system may be using the same access point.
It could be something as simple as your browser trying to send the address to a search engine instead of directly looking for the site.
When you’re trying to access it on mobile do you manually enter “http://” or “https://”? Those default to ports 80 and 443 respectively.
If you’re using nonstandard ports you may need something like “http://192.168.1.42:8080” to use http on port 8080 or any other nonstandard port.
Even if you are 100% sure your server is http or https try the other one to see if your error changes.
Bug bounty payouts correlate with how secure software is (more securely written software = larger bounties).
Your answer would be:
OS: Desktop < iOS < Android
Mobile: all other browsers <<< Chrome & Safari
Desktop: all other browsers <<< Edge & Safari & Firefox < Chrome