You definitely haven’t “updated both Knots and Core” since you can’t run both at the same time. You can’t also upgrade one to the other accidentally. You’d need to upgrade the one you’re running or follow the guide to switch: Guide: Switching from Bitcoin Core to Bitcoin Knots on StartOS v0.3.5.1
Gateway Timeout means the server is not there… it’s turned off, restarting, or you’re on a different network. A hard refresh should show the current state.
Ctrl + Shift + R (Win/Lin)
Cmd + Shift + R (Mac)