I wouldn't interpret it as a sign he's ready for solids, some people will tell you that increased appetite is a sign of readiness but that's not really true. Real signs of readiness for solids are being able to sit up (perhaps with a little support, such as on your lap), having the control to pick up food and get it to their mouths, losing the tongue thrust reflex and being able to chew and swallow. They should have all these skills together and very few babies do before 6 months.
Waking for extra night feeds happens for many reasons. Baby could be having a growth spurt, could be making up for being distractible and not feeding properly in the day, could be learning a new skills such as rolling or sitting and be waking to practice and then wanting you, could be teething and wanting to comfort feed, could be a change in weather waking them etc etc. This article from kellymom is useful
https://kellymom.com/parenting/nighttime/4mo-sleep/
There are things you can do to make it more bearable but theres probably an element of waiting for it to pass needed too. When my lo gets like this I try and understand the cause so I can do as much as possible to help, so for example make sure she feeds well in the day, using a quiet, darkened room if need be, make sure she naps well and gets plenry of fresh air and exercise in the day, check that her room is not too hot or cold at night, give her plenty of chewing opps in the day if she's teething etc. Then, if nights are really bad, we co sleep for a few days, just so I can get some rest. It usually passes within a week and we go back to normal nights.
