strelaysrv stopped unexpectedly on a server. Were might the log files to find the cause be located?
It logs to stdout, so check how you’ve set it up to run.
As Audrius already said: stdout. Beware of running the current strelaysrv in --debug mode. You’ll end up in 99,4 % of session.go:268: 1452 bytes from foo to bar log lines:
-rw-rw---- 1 syncthng synctgrp 7.2G Apr 9 23:59 relay-2018-04-09.log
-rw-rw---- 1 syncthng synctgrp 19G Apr 10 23:59 relay-2018-04-10.log
-rw-rw---- 1 syncthng synctgrp 22G Apr 11 23:59 relay-2018-04-11.log
-rw-rw---- 1 syncthng synctgrp 23G Apr 12 23:59 relay-2018-04-12.log
-rw-rw---- 1 syncthng synctgrp 17G Apr 13 23:59 relay-2018-04-13.log
-rw-rw---- 1 syncthng synctgrp 20G Apr 14 23:59 relay-2018-04-14.log
-rw-rw---- 1 syncthng synctgrp 26G Apr 15 23:59 relay-2018-04-15.log
-rw-rw---- 1 syncthng synctgrp 41G Apr 16 23:59 relay-2018-04-16.log
-rw-rw---- 1 syncthng synctgrp 18G Apr 17 11:19 relay-2018-04-17-old.log
-rw-rw---- 1 syncthng synctgrp 282M Apr 17 23:59 relay-2018-04-17.log
-rw-rw---- 1 syncthng synctgrp 617M Apr 18 23:59 relay-2018-04-18.log
-rw-rw---- 1 syncthng synctgrp 531M Apr 19 23:59 relay-2018-04-19.log
-rw-rw---- 1 syncthng synctgrp 321M Apr 20 23:59 relay-2018-04-20.log
-rw-rw---- 1 syncthng synctgrp 293M Apr 21 23:59 relay-2018-04-21.log
-rw-rw---- 1 syncthng synctgrp 261M Apr 22 23:59 relay-2018-04-22.log
-rw-rw---- 1 syncthng synctgrp 77M Apr 23 08:29 relay-2018-04-23.log
As seen, I disabled the debug line in session.go:268 on April 17th 
Thanks. Was sending logs to the big pit from 300.
nohup syncthing > /dev/null 2>&1&
meant
nohup strelaysrv > /dev/null 2>&1&