I use RFM69HW 433 MHz with a wire antenna (straight or spiral). When I start to test my devices, I had a range of about 100 - 150 m (transmitter in my house, receiver outside), so it was very good result for me.
Unfortunately, after building the nodes, now I have the stable range less than 10 m inside my house (I use maximum MY_RFM69_MAX_POWER_LEVEL_DBM (20)). Sometimes it is better, sometimes worse, it depends on various conditions.
Congratulations on such good results of your gateway, but I'm afraid that stable transmition will be much smaller.