A few days after this post I went to a friends house and while there I tried signing in and it still wasn't working, but I forgot to update you, so sorry about that haha.
But the main point of why I was reminded to update you here is because I randomly just decided to try again on my PC and it just worked. It also works on my phone using mobile data too, so the issue seems to have been resolved now.
Thanks again for trying to help and being transparent and down to earth while doing so :D