Is it illegal for the community not to pay the property fee and not let the vehicles in?

Break the law. There is a property service contract relationship between the owner and the property service enterprise. Property service enterprises are obliged to provide property services, and owners are also obliged to pay property service fees on time. If the owner fails to pay the property service fee as agreed, the property service enterprise can take corresponding legal measures to safeguard its legitimate rights and interests. However, the property service enterprises can't restrict the owners' vehicles from entering the community, which infringes on others' property rights and personal freedom.