DR: Cannot connect to primary server

We have 7.31 on Solaris_x86 5.7. The secondary server suddenly said 16:47:22 DR: ping timeout 16:47:22 DR: Receive error 16:47:23 DR: Receive Btree error 16:47:24 DR: Turned off on secondary server and keeps on saying 12:28:20 DR: Trying to connect to primary server ... 12:28:20 DR: Cannot connect to primary server 12:28:20 DR: Turned off on secondary server 12:28:21 Physical Recovery Started. 12:28:21 Physical Recovery Complete: 0 Pages Restored. 12:28:21 Onconfig parameter CDR_DSLOCKWAIT modified from 0 to 5. 12:28:21 Dataskip is now OFF for all dbspaces 12:28:21 Recovery Mode 12:57:02 DR: Secondary to Secondary 12:57:02 DR: new type = secondary, primary server name = database 12:57:02 DR: Trying to connect to primary server ... 12:57:02 DR: Cannot connect to primary server 12:57:02 DR: Turned off on secondary server when we stop and restart it. The primary server runs normally and can be pinged from the secondary, so I don't see why IFX cannot connect to it, nothing has been changed (so they say) on any of the two. How can I find out what went wrong? --Micha