There are quite a few folks desperate for fixed Marvell Wi-Fi drivers for Surface devices following bad drivers that were sent down through Windows Update in early August. The greatest impact seems to be on mesh type networks. You can, or course, roll back the bad driver. But if you need to test the “fixme” version, and intend to stay on 1903 until 1909 is “proven safe for mankind” (so to speak), there is an option.
It seems possible to join the Insiders Preview Ring to get the “fixed” Marvell Wi-Fi drivers for Surface devices without being forced to download and install 1909 if you are already running 1903. 1909 “should” be offered as an optional update and I’ve made a short video explaining the steps, as there are multiple restarts in addition to the specific order of steps that need to be followed. I’ve tested this and it works for me. I can’t guarantee that it will work for you, but the worst that can happen is, if you are running 1903 and 1909 does install, you can open the classic Control Panel, Programs and Features, view Installed Updates, and UNINSTALL the 1909 update.