Best neighborhoods for international students in Seoul?

I'll be starting my semester at Sogang University next month and I'm looking for a place to live. My budget is around 400,000-500,000 KRW per month. I've been looking at goshiwons and officetels but I'm not sure which area to choose.

I want somewhere with good public transport connections, affordable food options, and ideally some international community nearby. I've heard Sinchon/Hongdae area is popular but might be expensive?

Would love to hear from anyone who's been through this. What neighborhood did you end up in and would you recommend it?