Home Wifi NAT Type issues

Can anyone help me come up with a solution? I've been dealing with constant issues with my UPnP being not successful and my NAT type being strict on my Xbox. I am also have the same issue on my switch that gives me a NAT type D. I am at my wits end with this and absolutely appalled with everything. I have called multiple times and nobody seems to either want to help me or can help me. I don't know what else do next. I am currently on my 2nd router cuz the 1st one stopped throwing out an internet connection and now this router is giving me restrictions on both of my Xbox's and my switch. I have restarted my router and reset it multiple times I am out of ideas I really don't know what else to do. Can someone please help me cuz this is absolutely ridiculous that I am having all these issues and I haven't even had the wifi for 2 months. I am willing to try everything at this point and unfortunately cancelling isn't really an option it's the only option I have for wifi right now.