Regarding using older extenders with a new 3100 router. I mainly use the extender as a wired access port. Since older extender is connected via house coax, would the hardwire LAN ports still work (but not wireless function)?
We were having problems getting wireless upstairs in our house. Verizon advised upgrading our internet and router. We got the Gigabit service and this router. I can't tell that things are noticeably faster downstairs - never really had a problem before and aren't having problems now. But upstairs is worse than with our 75/75 service and ancient router. The internet connection is constantly being dropped on laptops and things take forever to load, even though it shows the wireless is working. Notice others are having this problem on these forums, but haven't found a solution. We are constantly having to reboot the router. My kids are rioting. Verizon customer service is overwhelmed in the pandemic, so we keep getting dropped trying to get to a human to help. I would suggest holding off on this router.