Why can't my phone (HTC One M8) connect to Wifi and Mobile Data after a factory reset?

[AC Question]

So, a few days ago, i decided to factory reset my phone, because it was getting slow and the battery wasn't holding up as it used to. After the factory reset, I went through the initial set-up wizard (Language, setting up accounts, etc.) but when the screen for connecting to a wifi network appeared, i filled it out, but it would not connect. I decided to skip that part, and come back for it later. When i did, i saw that it was giving me an error "Avoided poor Internet Connection" after it tried to connect for about 1 minute. I also noticed that my Mobile Data was not connected. I've been looking for answers for a while, but nothing. Trust me, I have tried so many tedious things like manually inputting network information. (Its not my router/modem, ive done multiple resets and crap for them across my home network, and one that me have nearby, both of them i cannot connect to. (When i did manually input the wifi information, it would connect, but the moment i tried to open anything that required me to use internet connection, it would instantly disconnect from the network.) I have also restored an old backup, but the problem persisted, across multiple other factory resets as well. My phone IS rooted, and i did the initial factory reset through my custom recovery. But, have since used the factory reset option in the phone's settings, to be sure it wasn't the problem. HTC support recommends I upgrade my software (which is on 5.0.1) but that may be a bit difficult without ANY internet connection. I also don't know why my phone would do something like this after 1 and a half years, because of my software version. This is the only time this has happened, and this was my FIRST factory reset, so i believe it is the reason why this is happeneing.