Uncomment these lines "--where status != 'OK'" to see if anything is NOT in OK state if there is that is causing the SYNC to STOP
-- SQL QUERY
-- Symmetric DS : MONITOR : HEARTBEAT / INCOMING / OUTGOING / MONITOREVENTS
SELECT node_id, host_name, getdate() as dtNOW ,heartbeat_time FROM [tablename].[dbo].[sd_node_host] with (NOLOCK) where heartbeat_time > '2022-01-01'
--SELECT * FROM [tablename].[dbo].[sd_context] with (NOLOCK)
SELECT * FROM [tablename].[dbo].[sd_outgoing_batch] with (NOLOCK)
--where status != 'OK'
order by create_time desc
SELECT * FROM [tablename].[dbo].[sd_incoming_batch] with (NOLOCK)
--where status != 'OK'
order by create_time desc
-- Symmetric DS : MONITOR
SELECT * FROM [tablename].[dbo].[sd_monitor_event] with (NOLOCK) WHERE is_resolved != 1
SELECT * FROM [tablename].[dbo].[sd_monitor_event] with (NOLOCK)
EDIT
here is the link for the symmetricds user guide.
https://www.symmetricds.org/doc/3.13/html/user-guide.html#_outgoing_batch
basically NE means it is ready for replication. Did you ever have it set up or is this a new setup that you are trying to get started?
EDIT 2 ENGINE CONFIGS
MAIN
engine.name=<SDS_MAIN>
db.driver=net.sourceforge.jtds.jdbc.Driver
db.url=jdbc:jtds:sqlserver://<IP>:1433/<DB>;useCursors=true;bufferMaxMemory=10240;lobBuffer=5242880
db.user=***********
db.password=***********
registration.url=
sync.url=ttp://<IP>:<PORT>/sync/<SDS_MAIN>
group.id=<GID>
external.id=000
auto.registration=true
initial.load.create.first=true
sync.table.prefix=sym
#start.initial.load.extract.job=false
compression.level=-1
compression.strategy=0
CHILD
engine.name=<SDS_CHILD>
db.driver=net.sourceforge.jtds.jdbc.Driver
db.url=jdbc:jtds:sqlserver://<IP>:1433/<DB>;useCursors=true;bufferMaxMemory=10240;lobBuffer=5242880
db.user=***********
db.password=***********
registration.url=http://<IP>:<PORT>/sync/<SDS_MAIN>
sync.url=http://<IP>:<PORT>/sync/<SDS_CHILD>
group.id=<GID>
external.id=100
auto.registration=true
initial.load.create.first=true
sync.table.prefix=sym
start.initial.load.extract.job=false
compression.level=-1
compression.strategy=0