NETGEAR C6250-AC1600 WiFi Modem Router Combo (Open Box)

Bought this thinking it would be a cheaper alternative to renting equipment through the internet service provider. Read it was "renewed" and I've had really decent luck with purchasing other "renewed" products both from Amazon and one of it's sister websites that sells refurbished or "renewed" electronics. Received the product a day ahead of the scheduled delivery, great job to Amazon and their delivery team (wish I could give stars for that). Set it up, got it connected and ready to use (FYI if you're using cable internet, THIS DOES NOT COME WITH A COAXIAL CABLE). The missing cable was no big deal seeing as I had a couple on hand from previous cable internet. Called up the internet service provider so they could connect the service to the modem, boom!! got it all fixed up and ready to go. From the jump the WiFi worked well. I tested the modem using my desktop and ethernet for my work computers, that worked good also.....then about an hour into using the modem, the WiFi signal started lagging real bad. This got to the point of buffering on my TV every 45min to getting kicked out of my video game every 20min when I played. I play on my TV, on my iPad and on my phone - ALL devices experienced the same thing. Using the WiFi on our phones was lagging real bad and we experienced terrible slowness on our laptops and phones. Being as I've had the internet service provider before with no issue in WiFi with this provider and another provider with a different modem, I knew right away it was not the service. It came down to either the modem or the 5 yr old coaxial cable I used. A week passes, still experiencing the terrible lag/glitch/slowness. I bought a new coaxial cable, replaced it and did all necessary steps to get me back online by unplugging everything, resetting the modem and etc. About 25-30 min into streaming a TV show, it started buffering and lagging again. About an hour after installing the new coaxial cable, the slowness and glitches from both my iPad and my phone started. Definitely NOT the coaxial cable (which is cool cause I have not thrown it away yet thinking it was old). I even tried moving the modem to a more central location in my house thinking the modem didn't spread across the house well enough. NOPE (far shot but I thought I would try every option). I've had the modem for a little over 2 weeks. Since having this product, I've experienced slowness/lagging/glitching on ALL my devices (cell phones, iPad, multiple TVs in the house, laptop, desktop using the ethernet, and my work computers since I work from home---my boss is NOT happy with me right now). Definitely not the internet service provider or the amount of bandwidth I pay for every month because I never had an issue with my previous modem. Not happy and will be returning. Not a good "renewed" product from this seller. Don't waste your money- go spend the extra $20-$25 and buy a new one from elsewhere.