Battlefront lag with otherwise solid PS4 download speeds

I have really been enjoying this game so far and have defended it on social media and review sites but it has recently become so laggy that I am considering requesting a refund.

My internet connection isn't the best but I still get 6-11mb download speeds which becomes 2-4mb on my PS4. This should easily be enough to play Battlefront with no lag. I have no issues with Call of Duty or even Netflix which requires more bandwidth.

My connection to the Battlefront servers has consistently poor and more laggy than CoD since purchasing but over the last week it has become extremely bad. I experience yellow or red connection daily and even when the game says I'm not having connectivity issues, I am a good second behind other players and cant run more than 10m without the game skipping back a step due to lag. This would be bad for any game but for an FPS, this makes it unplayable and frustrating!

I have tried everything to fix it, including: resetting the router, resetting the ps4, booting in safe mode, updating the system, opening all the ports the game uses on my router router, changing the DNS & MTU, changing the WiFi channel etc.

My brother has a much slower internet connection as me but has no issues with lag.

Is there anything else I can do to fix this issue or do I just need to request a refund?