So from time to time, I have a stable french talking partner who talks to me in french from time to time. He is from Roubaix in France and when he sends voice notes, I find that I have trouble understanding him, however, I don't have much (if any) trouble understanding or even making out french words/phrases from the french youtubers I watch who often come from the Paris region. I also used to talk to another french person and I don't think she was from the paris region, however, her french was very easy to understand and it was so clear.

So I guess what i am asking is, are there accents in France that can affect how I understand people from France? Do people from Robaix or the Lille area have an accent? What are some regions I should be aware of that the people may have an accent and how can I try to familiarize myself with how they speak?

Thank you in advance