@Emil How often is the settings UI collectively opened that this traffic could genuinely be a concern? This could be a super lightweight request, even just an http HEAD method to a CDN cached response that includes the version in one of the headers.
But let's say that even this traffic is too much, and you must avoid any network activity on Settings load. As soon as the "Check for New Firmware" button is pressed on the settings page, you could initiate this version check call to get the most recent version number. The next page should tell you either 1) that a new version is available and ready to be installed with an "Install" button (also showing the current version, the new version you will be installing, and a link to the release notes), or 2) that you already have the latest version with a "Back to Settings" button (e.g. "4.2.13 is already the latest version"). If there is a network issue, you could report that here with a "Retry" button.
If you are already checking and automatically updating the firmware every 24 hours, that information should be shown in the interface, too. Maybe an info button next to the "Hub Version" on that settings page that explains this. Ideally you would also show a log of the last N firmware updates, or the timestamp of the most recently installed update and link to its release notes at the very least.