> On Jul 7, 2015, at 12:42 AM, Meikel <meikel at fn.de> wrote: > > It's a D-Link DGS-1210-16 Switch. http://www.dlink.com/-/media/Business_Products/DGS/DGS%201210%2048/Manual/DGS_1210_Series_Manual_v4_00_EN.pdf What are the current settings on the switch for: Loopback Detection page 35 STP Global Settings page 38 STP Port Settings page 39 Under STP Global the "forward delay" defaults to 15 seconds... The same delay you're seeing.