There are some German books:
about home financing, which mention that you shouldn't buy a property with a rental yield lower than 4% or even 6% for older houses. In addition, you shouldn't pay more than 25 times your expected annual payment in case of 4% rental yield.
I'm located in rural area in Austria near the German border. The average apartment price is about 2000€/m² (still rising), the rentals are about 7€/m² per month. When using these rules about financing, there's no chance to get any property, at least in my area.
How can one get real estate without breaking one of these rules? Has this rule of thumb stopped working due to the low average lending rates? Or is this just a phenomenon of my region in Austria?