ID #1743

What to do if STP is blocking my server?


Your server is losing network connectivity while starting / using a (virtual) bridge or other Layer2 device at the server.


Possible cause:

The servers layer2 device has activated STP (Spanning Tree Protocol) and send via physical network card BPDU's to connected switchport. The switchport shut down the port due to security reasons and the server is not longer reachable.



  1. Activate rescue - mode (via CP, app or similar) with Webreboot of the server. (Note, the rescue mode will not start at this step!)
  2. Wait around 30 Minutes.
  3. Disable Rescue-Mode.
  4. Enable Rescue-Mode again with wereboot. Now the rescue-mode will start.
  5. Disable STP or filter BPDU's to switchport in your config.
  6. Disable Rescue-Mode and restart the server in normal mode.


Knows problems:

  • If rescue-mode does not start at step 4) please contact support.


Tags: Bridge, layer2, server, stp, virtualisation

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