Looking for a standard Gateway? How can a standard IoT gateway exist in the market where there are no standards set for IoT yet? It seems the so-called Standard-IoT-Gateway is a market manifested word and not a manufactured device. If you are sure about your business requirements and having clarity on what is needed and not needed. Maybe it’s an individual business choice, but otherwise, start exploring different types of Edge Gateways for various purposes. 

Semiconsoul’s SPIGWAY[Special Purpose Industrial IoT Gateway] Series of Gateways.