It will most likely to be down to the WiFi channel in use on the new DG8041W router clashing with other routers in your area. Have you tried changing the channels it uses to the same as your current router?
To tell you where to find out what channel your old router is using, I first need to know the make/model of that router, as you have not said which one you have.
If you log into the router & go to:-
Home Network > Wireless Settings > Advanced Settings
You will see the channels used for each band there.
Hi there no a I actually just put the new router in the cupboard and am using my old router as it’s much faster with better wifi I checked the settings in my old router and they are all on auto the new router is so much larger aswell twice the size of my current super router also there is only 1 like on the new router the old super router has more lights giving you more information