Ive got same problem as 7eggert but in ver minecraft 1.12, seems fluiduct from Thermal Dynamics doesn't work.., and there isn't yet port EnderIO to 1.12...
My test setup is: drum or portable tank from (TD) - hardened fluidduct with servo -> deep resonance tank (ofc. setup to accept) and Liquid monitor to control ( or in simpler setup just lever ).
Ive tried xnet and didn't work for me too,..
Thanks you for advice
PS. After restart client everything works fine, strange ... thanks