The question here is - did you put a checkmark beside the ‘Printing support’ in the installer? If not - then install the minimum necessary parts of the printing capabilities. I had the same problem with a weird Apple html file replacing my .conf file (repeatedly) but I didn’t track it down. I started from scratch with installing only what was needed to print - in your case what is needed to print over the network.
If you work through the wiki on here - ONLY do the parts that you are sure apply to your use case! (for example - ignore the stuff about HP printers).
There are lots of people that have things going well - and Brother printers usually have the drivers available - so it shouldn’t be too bad. Hang in there!