Hi, in some phones you can disable wifi in the preferences, but in others, this is not possible. I assume the OP was not able to disable wifi in preferences (or perhaps only had “airplane mode”, which also disables cellphone reception).
I personally don’t particularly like K9. In addition, Android, but also Chrome for Windows and other platforms, will connect directly to the google websites, such as gmail. I once posted a detailed discussion, but moderators deleted it. I don’t mind rewriting what I can remember, but if it’s not suitable for the website, no problem. However it is unadvisable to rely too much on K9. Actually at this point it is unreliable to rely upon any single filter.
A smartphone is, unfortunately, a platform where the user is the product. They need to grab our personal info (you realize our phones knows which time we wake up and which time we fall asleep, whom we call and for how long, the websites we visit, even what we are thinking – we usually write that into google) and they need to push advertising and other unwanted garbage; the aim is to keep our attention focused on the device for most of our waking hours. Of course connectivity is crucial to that “business” model.
The Android (a unix-family operating system) has a filesystem which is hierarchical. The top directory is / (it is also called the root directory) and contains both files and subdirectories. For example typical subdirectories of the directory / are /etc /bin /usr and so on. In turn those contain files and sub-subdirectories. However, in many cellular phones, one can not even see the directory structure, or in other cases, the important files are read-only and can not be modified by the user.
Please be careful with modifications because it’s very possible that the phone will decide to access the internet anyway, except will do that on the cellular network (at your expense).
Please let me know more precisely what you are trying to do, and if I know how, I will tell you. Are you trying to block the web browser? Are you trying to block all connectivity via wifi? Are you wishing to keep some apps connected (such as email) and block others?