Best way to refi non-owner occupied single-family

I see a lot of people talking about having between 4 to 10 single-family homes under normal financing. But I was wondering if that is possible with non-owner occupied homes. I started buying and renting out homes around a year ago and soon I will have four rental units. I finance them by taking out a personal loan payment cash then rehabbing them and re-financing. When I went to refinance them however the bank told me because they were rental properties I had to use a commercial loan. I have my loans through a local Per folio lender who charges 6% and will only go 15 years. They will only do 70% loan to value and I would like to get a higher LTV if possible. And of course a lower interest rate than 6% if I can. I was wondering if other people had the same issue with non-owner occupied properties or if I should be looking at a different loan product.