PC so match the 2001: : 1/16201 2: : 1/16. Server with 2001: FFFF: : 1:1/16,
When delete 2012 segments, ping. When you don't delete, ping PCping server impassability, behind the initial guess is now 2001 FFFF subnet (ID), because when removing FFFF, can ping again; For bosses to solve!