iMessage taking long to deliver iOS11

I'm using an iPhone 6s on the latest OS and ever since the iOS 11 update last year I've been having a lot of trouble using iMessage. Whenever I send a message it would take 20-60 seconds to deliver, as well as to receive messages. People I have been talking to have told me that their messages take awhile to show as 'Delivered' when messaging me as well. I have iMessage enabled on my MacBook Air, also on the latest OS and it sends and receives messages fine. If I have both open at the same time, I'd be able to send and receive messages on my mac perfectly fine and the messages wont show up on my phone until later, sometimes several minutes if there is a lot of chat happening.

I have tried many things to fix this and looked all over online for answers, tried everything and hasn't worked. I have changed my iPhone battery to a new one, re-installed iOS from a clean install as well as deleted all my messages. Nothing seems to work. Please help.