You can stick with your current modem and buy only switch with wifi facility. But, buying a new modem will cut your mothly charges with no service from your ISP about modem.
SO, you can buy modem if you are sure that you donot need ISP to rectify any sort of issues related to modem. They may also say all the problems are arising because of your modem and they may not provide even a single service other than connection.
Think about all this and then buy swith or modem.
I am not here to rant about my ISP, but seriously they are not going to help a bit in cutting down my bills. Since they charge a non-refundable, one time charge for the modem(approx. equal to it's cost) and almost 5% of the cost as 'rent' of the modem alone every month, I decided to purchase my own Modem.
They gave me a Sterlite SAM300(TM)AX ADSL2+ Modem(12V/1A). [4 RJ-45 ports, 1 RJ-11, 1 USB port, Power On/Off Button, and Power-In port]
I am a bit confused with what should I buy. The scenario is as follows:
At my place there are atleast 2 devices connected to the Internet almost all day long, so I need more than 1 RJ-45 port(since not all have WiFi connectivity, and sometimes I need to setup a LAN for file transfer). I need the WiFi facility, currently lacking in this Modem(if I ask my ISP to issue a WiFi enabled modem, there would be yet another one time charge, apart from an increased monthly rental!). As far as I know if a buy a router alone, things won't work. I'm confused between buying a modem with WiFi or a Router+Modem with WiFi. Or if there can be another suggestion(apart from changing my ISP), I would be grateful. I have also found a budegt friendly Router+Modem - TP-LINK TD-W8951ND but I am not sure if that'd be too much for my requirement and also if it is a good enough device(I don't know much about TP-Link, though my experiecne with Netgear has been good enough)