Cap number of connections

Support
1

I have two Syncthing instances that are located half a world apart from each other. Tests regarding the number of connections revealed that there is a substantial increase in transfer speed to be gained by maxing the number of parallel connections.

Picture1
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Picture2
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There is no issue related to CPU or RAM usage.

Questions:

  1. Is there a way to raise the cap of 128 connections?
  2. Am I the only one that notices this performance boost? I guess it helps to overcome the throughput limitations of single TCP streams caused by high latency over large distances.
  3. Are there other Syncthing settings I can use to optimize the transfer speed?
2

Tell me more about your setup. I’m trying to see the situation where Syncthing would even have 128 block requests in flight at the same time.

3

Syncthing A is connected via Starlink, Syncthing B has a public IP. Like I said the two instances are 20000km apart so a lot of intercontinental cables and servers in between. The link is over TCP WAN. I use the link to sync archived files (200MB) one-by-one.

Number of connections Average transfer speed [Mbps]
24 12
24 11
32 13
32 16
48 21
64 20
80 29
128 40
128 47

It is clear that a plateau has not been reached yet.

4

This feels like you’re just circumventing limits on maximum in-flight data that way.