syncthing from windows to linux

Did you check what I suggested?

Yes I did, but there is all OK. also resources are below 15%

Including disk IO?

What are you trying to diagnose here? It looks like everything is ok.

yes even IOs. but I foud out server have somekind of connection problems. It loose connections regularry. need to find out why? syncthing looks like work ok.

Well check the logs for reason for disconnect.

nothing in logs for that

There is always a message about disconnect, so perhaps you are checking the wrong logs.