Factorio Forums

Apparently reading through a ridiculously long shared blueprint library is treated as idle, and you are kicked if you spend enough time browsing through blueprints.

FIX: moving mouse over blueprints and books, and scrolling the window, should reset the AFK/idle timer.

The AFK system detects any input actions sent to the player and browsing GUIs doesn't generate them (as to not waste network bandwidth and because it doesn't need to). You'd get the same AFK-kick if you sat and scrolled through the logsitic network GUI - the game needs some input from you that changes the game indicating you're still around.

In this case simply clicking something in your inventory would be sufficient.