How to test Netgear C3700 modem/router when loosing connection frequently?

Hi. We lose internet connection at our new address several times a day. It got worse lately. We used the same internet service and the same modem/router at the previous address with a lot less interruptions. I can access the router data etc, but I do not know what I need to look at to verify if there is an issue with  the Netgear C3700 Modem/Router or with the internet service. One thing what I have noticed, when the connection drops, neither Netgear Genie, neither my computer shows it right away that there is no connection. There is a delay before they show it. However, I cannot open webpages at that time, so I know it is gone again. How can I test if my modem/router is good or bad? Thank you.