Hi @wclayf,
Thanks a lot for the tips. I tried multiple ways (using ways suggested by you as well) to set net.core.rmem_max inside the container but have not succeeded yet 
Some errors I encountered when trying to configure it (putting these here so that anyone encounter the same errors can search for the solution if anyone come up with any idea):
(when trying to set sysctls in docker-compose.yml)
OCI runtime create failed: container_linux.go:349: starting container process caused "process_linux.go:449: container init caused \"write sysctl key net.core.rmem_default: open /proc/sys/net/core/rmem_default: no such file or directory\"": unknown
or
(when trying to configure from the container's shell)
sysctl: error: 'net.core.rmem_max' is an unknown key
Will give you the update when I’ve found a way.
Thanks a lot.