Not sure if this was picked up when I originally posted it, or if this
feedback is useful but:
I noticed some rtl8169 driver changes in 4.18.15, pulled that from git
last friday and rolled it and did some bandwith intensive rsync tests
etc that would provoke the problem quite reliably before, and got no
reaction.
Gentoo released the gentoo-sources for 4.18.16 on Sunday and I switched
back to using this kernel, and this has been stable for 3 days now,
versus the problem traditionally turning up within 2-12 hours, again
suggesting the problem has gone away (or at least significantly changed).
Just to confirm that this seems to have fixed things for me, and to
thank you for all the time and effort (both on the relevant module and
more generally).
Iain
