Below are my proposed additions to the README file, assuming we don't want to
silence the warning.
I've added a short section on logging too.
Index: pkg/README
===================================================================
RCS file: /cvs/ports/net/syncthing/pkg/README,v
diff -u -p -u -p -r1.9 README
--- pkg/README 1 Jan 2026 22:24:37 -0000 1.9
+++ pkg/README 26 Jan 2026 13:18:14 -0000
@@ -22,8 +22,8 @@ Starting via RC script
Syncthing can be started via the included RC script, thus running
Syncthing as a system service. This is fine for single user
configurations. Under this mode of operation, Syncthing runs as the
-_syncthing user, and the default location for folders is
-${LOCALSTATEDIR}/syncthing.
+_syncthing user (or whatever `syncthing_user` is set to in RC), and
+the default location for folders is ${LOCALSTATEDIR}/syncthing.
Starting Manually
-----------------
@@ -45,6 +45,16 @@ This will result in a new tmux(1) sessio
boot. The user can later use `tmux attach` to view and control their
Syncthing process.
+Logging
+=======
+
+By default, logs are not saved anywhere; but you can read the logs
+for the current session on the web GUI.
+
+To log to a file, use `syncthing_flags`. Example:
+
+ syncthing_flags="--log-file /var/log/syncthing/syncthing.log
--log-max-old-files 5 --log-max-size 2000000"
+
File Descriptor Limits
======================
@@ -87,3 +97,16 @@ Another option is to turn off the file w
This will result in much reduced file descriptor usage at the cost of a
(configurable) latency. See "watch for changes" and "full rescan interval" in
the "advanced" tab in a folder's settings (on the web UI).
+
+UDP Buffer Size
+===============
+
+quic-go requests about 8 MB of UDP buffer space. On some platforms, it is able
to increase the limit automatically on startup. On OpenBSD this fails with the
following warning:
+
+ 2026-01-24 12:33:01 INF failed to increase receive buffer size (wanted:
7168 kiB, got 0 kiB). See
https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes for details.
+
+We can manually increase it by changing `net.inet.udp.recvspace`.
Unfortunately, this limit can only be raised to a maximum of 2097152 (approx. 2
MB). For context, see the discussion at
https://github.com/quic-go/quic-go/issues/3476.
+
+ # sysctl net.inet.udp.recvspace=2097152
+
+Add that to sysctl.conf(5) to permanently set it.
On Sunday, January 25th, 2026 at 13:00, Douglas Silva <[email protected]> wrote:
>
>
>
>
> Hi,
>
> When you start Syncthing, one of the first log entries is this warning:
>
> 2026-01-24 12:33:01 INF failed to increase receive buffer size (wanted: 7168
> kiB, got 0 kiB). See https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes
> for details.
>
> The linked wiki page explains that quic-go tries to automatically increase
> the buffer size on some platforms (not BSDs), and it has instructions for
> manually doing it on others; but the section on BSDs doesn't apply to
> OpenBSD. There is an open issue [1] about it.
>
> Someone there has figured out that the sysctl variable to change here is
> "net.inet.udp.recvspace", but it can only be increased to about 2 MB
> (2097152) — well below the target 7.5 MB (8441037). I have no idea whether
> quic-go is able to work properly with this. Either way, the warning persists.
>
> So, my idea is to:
>
> 1. Modify our package README with instructions to increase the buffer size to
> maximum.
> 2. Silence the warning by setting the variable
> "QUIC_GO_DISABLE_RECEIVE_BUFFER_WARNING" [2] [3]
>
> What do you think?
>
>
> [1] https://github.com/quic-go/quic-go/issues/3476
> [2]
> https://github.com/quic-go/quic-go/blob/4a8af22606c2d237da39212a734b80026a9a0bb0/sys_conn.go#L59
> [3] https://github.com/quic-go/quic-go/issues/3801#issuecomment-1882365505
