I just moved to JC a few months ago and I had the exact same problem. My roommate and I must have contacted about thirty different listings using several different websites and apps with very few replies. Even calling places/people directly and leaving messages for days didn’t get us anything. The only thing that worked for us was (luckily) finding a quality realtor, and while her broker fee was expensive it was 100% worth it for us. We wouldn’t have gotten our current apartment without her help. I obviously don’t know your financial situation, but if you have the means to work with a realtor it could make a difference. Also, getting in contact with apartment complexes was easier than individual landlords/realtors for us, so that could also be an easier option for you as well. Best of luck to you!