Nighthawk ac1900 c7000v2 has significant packet loss and high ping in gaming and video calls

I am completely baffled by my internet problems right now. I used to have a different router modem combo from netgear that worked pretty well for me, but after 3 years I started noticing problems (I started noticing it about a month and a half ago). In all the games that I played, I noticed some pretty severe latency problems and packet loss. This is across PC and PS4, wired and wireless connections. I checked with my ISP and they said things looked fine from their end. So I in turn bought a new router modem combo (Nighthawk AC1900 C7000v2) thinking that the hardware of the previous model was broken, but I continued having similar problems. I am pretty certain the hardware of this new model is fine, so I called some friends that live by me with the same ISP that play the same games that I do and they said they were having no issues. After this information, I called my ISP again and they sent a tech out to me and he fixed a couple of faulty connections. It still didn't help. They sent another tech out again and fixed a couple other things that already looked ok but were not quite "new" and it still didn't help. They think the cable connected to the modem is functional and good. This leads me to think that something is wrong with my router/modem. Therefore, I tried port forwarding and disabling and enabling different things from suggestions I found on the internet and it made no difference. It might be a firmware problem, but I don't know what to do next. I also live in an apartment complex, so that may factor some into this, but I am massively confused.