ah hun, no baby ever lets you settle into a good routine for long...drives you crazy
He might be going through a rest period where he just isn't as hungry, or he might be too tired at dinner time to eat. Sometimes my 4yo still does this. Often i make sure they have a proper meal at lunch so they only have a light dinner.
I have learnt over the years that for us solids have nothing to do with the quantity or quality of sleep (or lessens the wakeups) - but hey that might be just us.
FWIW my 17monther has only just gone to 3 feeds per day - previous to this (like 2 weeks ago) he was still having up to 8. Solids still aren't their main source of nutrition at that age either, the milk should still be.
For us an earlier sleep definitely works better. DS goes to bed anywhere from 10ish to midday - like I said he is older. We have been doing this for some months though.