HI,
Please try the following changed to the udm_manager.cfg:
The first thing I would do is tune some of the memory settings
setup/datomic/memory_index_max = 512m
setup/datomic/object_cache_max = 1024m
startup/opt/java_mem_max = -Xmx4g
setup/datomic/heartbeat_interval_msec : 30000
Also check
find out if the database server is under a significant load. I’m finding that udm_manager is particularly sensitive to high load and will miss a heartbeat, triggering restarts.