# OT architectures The FlowFuse server lives up in the IT infrastructure; the Remote Instances live down in the OT environment on the equipment. The server deploys to and manages them across the IT/OT boundary, while each Remote Instance keeps running locally if the link drops. **Use it when** — IT owns and hosts the platform, but execution must sit next to the machines in OT. The FlowFuse server sits inside the plant, firewall-segregated in a DMZ. It reaches corporate systems through a controlled uplink to a Remote Instance up in the IT network, and manages Remote Instances on IPCs and embedded hardware in the OT network below. Nothing reaches OT except through the firewalls. **Use it when** — Security policy keeps the platform inside the plant boundary, exposed only through a DMZ. The DMZ pattern taken to its extreme: a self-managed FlowFuse runs on a server inside an isolated OT network with no internet at all. It manages that site's instances and devices entirely within the OT boundary — nothing goes in or out. **Use it when** — Site security policy forbids any internet traffic in or out of the OT network. Instead of a Remote Instance on every device, deploy one FlowFuse server close to the line and run several Hosted Instances on it — each doing the work an edge device would have done, talking to its equipment directly. Fewer physical boxes to buy and maintain, same separation of concerns. **Use it when** — You want the edge workloads consolidated onto nearby server hardware to cut device count.