Worth stating the boring answer louder: most complaints about a provider box are really wireless complaints, and wireless is a placement problem before it is an equipment problem.
Before spending anything, move the box off the floor, out of the cupboard, away from the metal and roughly central. I have watched people replace an entire setup to fix something a two metre move fixed for free.
If it is genuinely the wireless and not the location, add an access point and leave the routing alone. That is the cheapest real upgrade and it skips the whole bridge-mode conversation.