Seem like a pretty low-rise area, that is, you are not surrounded by skyscrapers! So you should be getting a good range.
There are many parts to LoRaWAN that can cause issues, some you read about on the forum which are usually resolved once the problem is found or the person fixes it and tells no one.
As well as checking all the connections, is there another device/node you could use just in case there is an issue with the Heltec module?
It would really help if you had another node of a different brand which you could compare.
Also make sure you really have an 868 MHz version of the node hardware, and aren’t telling a 915 Mhz version to operate at 868 MHz where the RF networks are mis-tuned. Nothing in a node “knows” what frequency the surrounding circuitry was designed for, so it will quite happily try to operate on the wrong band if you tell it to.
Note also that you are using only relatively fast spreading factors 8 and 9. As I understand it, in EU868 you have all the way up to SF12 available - each step doubles airtime which has a power and capacity cost, but it does increase range.
I would install four RAK7249 gateway and I would have some guide to find correct position, heigth and antenna type. May you please support me in some way?