Henry Deacon was aware of this system, but referred to it disdainfully as 'ancient' and very dangerous. No one uses it much anymore once they get to the point of true interplanetary travel and communication. You have an experience of shooting through wormholes that can take quite some time, rides like a rollercoaster, and can involve vivid hallucinatory-type experiences.
If you are not properly trained you can experience permanent schizophrenic symptoms after being put through an ancient stargate system. By comparison, the 'modern' system is so quick and easy to use there literally is no time elapsed. The doors close, the doors open and you're done.
The ancient gate network will only translate living, organic materials. Weapons and such do not make it through, as well as inorganic fabrics such as polyester, elastic or rayon. You cannot bring any tools, supplies or provisions through with you, except for fruits, vegetables and such. Modern systems do not have this problem. The Ancients deliberately designed the gate network this way to facilitate peaceful exploration and interplanetary communication.
Our insiders here on Earth fear what might come through the gate, and Daniel said the last he'd heard as of the mid-1980s was that it was buried in the Antarctic ice to quick-freeze anyone or anything who tried to get here by said means. This would emerge as an 'error message' from the other end of the gate for any would-be traveler.