Per a new government spending bill signed by congress in December as an update to the Communications Act, a new "consumer right to accurate equipment charges" provision prohibits internet service providers (ISPs) from chaging customers for equipment that the customer themselve provide. This is an egregious and unjustified money-making tactic practiced by some ISPs for years. Even the monthly "rental" or "leasing" charge for ISP-supplied modem/routers is of dubious moral standing since for the amount that a user pays in a year they could've just bought one themselves outright.
Check your monthly statement from your ISP. If you are currently paying a monthly fee to "rent" or "lease" your modem/router, you could save serious money by just purchasing the same model yourself on the open market.