Ethernet and Wireless Dropping Consistently

(For a little extra detail we were having this issue earlier this year despite our modem and router working perfectly find before. We were told our modem was no longer supported by cox. So we purchased a new modem. Had issues with disconnecting. Purchased a new router because they said they couldn't see our router connecting to the modem. We had speed issues and disconnects happen at our new location despite it working just fine at the old location. Tech came out and said connections look great. It's our router that's the issue. Spent a pretty penny on this new router. Speeds are better but still random disconnects)