https://userapps.support.sap.com/sap/support/knowledge/en/2772985
2772985 - RFC Destination SAPXPG_DBDEST_* fails with "ERROR: rexec failed" | SAP Knowledge Base...
Fom DB13 transaction, you find that scheduled Job to update database statistics is getting failed: SXPG_COMMAND_EXECUTE failed for BRCONNECT