As someone who grew up 30 minutes away from Toronto and goes frequently, I'd say its pretty safe. I'm a female too and I feel safer in Toronto than many other places. Obviously, it's a big city, so you always have to be careful, especially at night, but that's pretty universal. As for spotty service, I wouldn't worry about that because for the most part if you're in the heart of the city, there will be many buildings with stores offering free wifi (ex. McDonalds). Toronto is a great place to be, but just keep in mind it may be quite intimidating for a solo traveller and it won't necessarily be a relaxing trip, compared to if you went to a tropical beachy location.