Ok after collecting Logs for a day now i see a lot of perfect entries, but there are two errors which may be a hint to my problem:
ERROR piecestore download failed {"Piece ID": "YJDV5FMPFRPH6GDWAADYUG5OUOSLPMOH5KWH54S3GD3AN3LCNXEQ", "Satellite ID": "12L9ZFwhzVpuEKMUNUqkaTLGzwY9G24tbiigLiXpmZWKwmcNDDs", "Action": "GET", "error": "trust: rpccompat: context canceled", "errorVerbose": "trust: rpccompat: context canceled\n\tstorj.io/common/rpc.Dialer.dialTransport:310\n\tstorj.io/common/rpc.Dialer.dial:267\n\tstorj.io/common/rpc.Dialer.DialNodeURL:177\n\tstorj.io/storj/storagenode/trust.Dialer.func1:51\n\tstorj.io/storj/storagenode/trust.IdentityResolverFunc.ResolveIdentity:43\n\tstorj.io/storj/storagenode/trust.(*Pool).GetSignee:143\n\tstorj.io/storj/storagenode/piecestore.(*Endpoint).VerifyOrderLimitSignature:134\n\tstorj.io/storj/storagenode/piecestore.(*Endpoint).verifyOrderLimit:62\n\tstorj.io/storj/storagenode/piecestore.(*Endpoint).Download:467\n\tstorj.io/common/pb.DRPCPiecestoreDescription.Method.func2:1004\n\tstorj.io/drpc/drpcmux.(*Mux).HandleRPC:107\n\tstorj.io/common/rpc/rpctracing.(*Handler).HandleRPC:56\n\tstorj.io/drpc/drpcserver.(*Server).handleRPC:111\n\tstorj.io/drpc/drpcserver.(*Server).ServeOne:62\n\tstorj.io/drpc/drpcserver.(*Server).Serve.func2:99\n\tstorj.io/drpc/drpcctx.(*Tracker).track:51"}
and
WARN orders DB contains invalid marshalled orders {"error": "ordersdb error: database disk image is malformed", "errorVerbose": "ordersdb error: database disk image is malformed\n\tstorj.io/storj/storagenode/storagenodedb.(*ordersDB).ListUnsentBySatellite:169\n\tstorj.io/storj/storagenode/orders.(*Service).sendOrders:177\n\tstorj.io/storj/storagenode/orders.(*Service).Run.func1:134\n\tstorj.io/common/sync2.(*Cycle).Run:92\n\tstorj.io/common/sync2.(*Cycle).Start.func1:71\n\tgolang.org/x/sync/errgroup.(*Group).Go.func1:57"}
and
WARN orders some unsent order aren't in the DB {"error": "order not found: order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: 442HRDF7YJEGRPCPVXCR7HFWXI; order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: YXQAP6BCHVECLAIRJS6ECOT4GE; order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: 5YKPUTPFB5HONDUXXHMXMMN5NE; order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: WYJKHJ6745EMNH672UFWY7PZIM; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: 6ALSQOXVPJCSBAG2M4E4VOJAVQ; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: MX74ZVOAKNGDBERGFYYOAGA6Q4; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: Y5NCPVBUQRHLDPOKLZDQY4UT3I; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: 77LJ75TDVNHQ7FKOFWZBCTRDBU; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: LFIE5E67NJBXLG6G6NZIK7HXGI; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: GFZXWYVQQBDSRKFQCWQ3NKFWBE; order not found: satellite: 12EayRS2V1kEsWESU9QMRseFhdxYxKicsiFmxrsLZHeLUtdps3S, serial number: 5JOYAEJ7JJAHLIFK43DY2K22V4; order not found: satellite: 12EayRS2V1kEsWESU9QMRseFhdxYxKicsiFmxrsLZHeLUtdps3S, serial number: 3LLOVWDC4RFXBMZQAFLCOSYNF4", "errorVerbose": "order not found: order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: 442HRDF7YJEGRPCPVXCR7HFWXI; order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: YXQAP6BCHVECLAIRJS6ECOT4GE; order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: 5YKPUTPFB5HONDUXXHMXMMN5NE; order not found: satellite: 121RTSDpyNZVcEU84Ticf2L1ntiuUimbWgfATz21tuvgk3vzoA6, serial number: WYJKHJ6745EMNH672UFWY7PZIM; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: 6ALSQOXVPJCSBAG2M4E4VOJAVQ; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: MX74ZVOAKNGDBERGFYYOAGA6Q4; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: Y5NCPVBUQRHLDPOKLZDQY4UT3I; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: 77LJ75TDVNHQ7FKOFWZBCTRDBU; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: LFIE5E67NJBXLG6G6NZIK7HXGI; order not found: satellite: 1wFTAgs9DP5RSnCqKV1eLf6N9wtk4EAtmN5DpSxcs8EjT69tGE, serial number: GFZXWYVQQBDSRKFQCWQ3NKFWBE; order not found: satellite: 12EayRS2V1kEsWESU9QMRseFhdxYxKicsiFmxrsLZHeLUtdps3S, serial number: 5JOYAEJ7JJAHLIFK43DY2K22V4; order not found: satellite: 12EayRS2V1kEsWESU9QMRseFhdxYxKicsiFmxrsLZHeLUtdps3S, serial number: 3LLOVWDC4RFXBMZQAFLCOSYNF4\n\tstorj.io/storj/storagenode/storagenodedb.(*ordersDB).Archive.func1:193\n\tstorj.io/storj/storagenode/storagenodedb.(*ordersDB).Archive:213\n\tstorj.io/storj/storagenode/orders.(*Service).handleBatches.func2:238\n\tstorj.io/storj/storagenode/orders.(*Service).handleBatches:262\n\tstorj.io/storj/storagenode/orders.(*Service).sendOrders.func1:189\n\tgolang.org/x/sync/errgroup.(*Group).Go.func1:57"}
There are these three entries and than thousands of successful downloads logged.
Next step: I will try to repair the database.
Edit: Shame on me i realize that I saw this error a long time ago (could be around the beginning of may) and try to fix it. I realized that the repair-process of my orders.db with a size of nearly 2,5GB will last a loooooooong time, even on my SSD-Space.
I skipped it cause the node was - like i saw on the dashboard - running smoothly.
No I started the process 30min ago, processed 10,5MB of 2,4GB. I will let it run, we will see.
Fortunately there is no punishment caused by downtime till now xD