Update. Can confirm deleting the container and only the Valheim directory followed by reinstall got it all working.
Ran it for a few hours with no players - all good.
With two players (one local, one not), it was stable for a few hours, but then things went a little goofy leading to a disconnect and the gameserver restarting. I think the network warnings are the ones that have already been discussed post-patch (?). The error is the same I was getting before the reinstall solution. I can't say for sure, but it seems to happen about an hour into playtime, so perhaps when it's checking for updates or doing the world save?
The result is about 30-45 minutes of lost progress (buildings, ships/carts).
We tried using the public listing in-game. Will not try direct IP connect (in-game).
src/steamnetworkingsockets/clientlib/steamnetworkingsockets_lowlevel.cpp (1276) : Assertion Failed: SDR service thread gave up on lock after waiting 93ms. This directly adds to delay of processing of network packets!
src/steamnetworkingsockets/clientlib/steamnetworkingsockets_lowlevel.cpp (1276) : Assertion Failed: SDR service thread gave up on lock after waiting 93ms. This directly adds to delay of processing of network packets!
src/steamnetworkingsockets/clientlib/steamnetworkingsockets_lowlevel.cpp (1276) : Assertion Failed: SDR service thread gave up on lock after waiting 93ms. This directly adds to delay of processing of network packets!
/opt/scripts/start-server.sh: line 140: 62 Killed ${SERVER_DIR}/valheim_server.x86_64 -name "${SRV_NAME}" -port ${GAME_PORT} -world "${WORLD_NAME}" -password "${SRV_PWD}" -public ${PUBLIC} ${GAME_PARAMS} > /dev/null