Erasmus Ladder Not Connecting to Computer – Router Light Red and Ladder Identification Steps
Last updated: Oct 29, 2026
Problem
The computer cannot connect to the Erasmus Ladder. The router (network box) shows a red light on port 3, indicating a network link failure between the ladder and the controlling PC.
Details
Symptoms: Connection failure on startup or during use; red indicator light on port 3 of the router/switch; cable checks and router restarts have already been attempted without restoring the connection. The issue prevents any experiment from being run.
Solution
1. In the ErasmusLadder software, close any open experiment via File > Close.
2. Go to File > Ladder Identification.
3. Switch the Erasmus Ladder OFF.
4. Click the 'Detect' button in the Ladder Identification dialog.
5. Switch the Erasmus Ladder back ON and wait for detection to complete.
6. Note the result reported:
- 'A ladder [Ladder ID] is connected' – connection is restored; proceed normally.
- 'An unidentified ladder was found' – a ladder is detected but not recognized; note the ID and contact Noldus support.
- 'No ladder found' – the hardware link is still broken; check all Ethernet cables between the ladder and router, try a different cable or port, and contact Noldus support if the issue persists.
7. If the red light on port 3 of the router remains after the above steps, the router or network interface on the ladder may require replacement. Escalate to Noldus hardware support.