Why can’t you connect the DSi to the internet? Is the WiFi damaged?
Is there really a reason to update? I mean, most of the updates did nothing else than blocking exploits and/or flashcarts. https://dsibrew.org/wiki/System_Menu
The only reason I can think of for an update was accessing the (now defunct) DSi-Shop. Even the games do not need a higher firmware (in contrast to the 3DS where games do need a specific minimal firmware and come with updates on the cartridges).
DS-Lite/phat only support WEP or no encryption. But it is possible to connect a DSi to modern WPA(2) networks -- something with "advanced setup"
But anyway, having seen your second question, an update is not going to help you with softmodding the DSi (because the DSi Shop is defunct). A DSi on 1.0 probably does not have any DSiWare, especially no Flipnote Studio.
The only options you have are:
* wait and hope “Failzone” will eventually be released
If it is a DSi, AND it has flipnote installed, (Where flipnote is installed from factory) Then you need to update the DSi and load up the shop at least once for the SD card management to show on Dsi settings
he said this: "James & the Giant Peach is so unrealistic because peaches aren't giant in real life. Roald Dahl really should have done some research before writing this terrible and unrealistic book. Entire generations of kids have probably been ruined because they thought that peaches could be really big."