There is nothing wrong with your PC, it's just old.  The wifi card in your PC uses wireless N technology, which was released around 2007, also known as wifi 4.  Taking into consideration of building structure, signals interference, and network settings, it provided a real life connection at 72 Mbps to your PC, therefore your download speed could not go over 72 Mbps. As the technology progress, wireless AC (aka wifi 5) could provide a solid 867 Mbps (as pictured in my previous post) and more recent wireless AX (wifi 6), which is capable of 3 Gbps or more.  The wifi cards themselves still have the same look and form factor to your Qualcomm and replacement is just a simple swap in. Just pointing you to the right direction and the choice is yours to make.
I don't think anything is broken, but I am unable to reliably connect to the internet and browsing is so slow that it is unusable.  I just upgraded my modem and service, too.  That actually made things worse.  I tried installing the Dell updates, but some wanted to install drivers/files older than what I have.  What am I supposed to do?  I upgraded all the "critical" ones.  I also ran across FirmwareTPM.exe that had big red 'x's under Maintenance.  Other threads say Dell is aware of this issue, but there is nothing about it.  Is that causing my problems?  This was my first Dell...it will probably be my last. It seems to run fine and fast enough except for connecting to the internet?  What the problem?  I have spent 2 months with Cox and trying to troubleshoot myself.  Something's gotta give.  This is crazy for people to have to do all this.  I could with < Windows 7, but they wanted control with Windows 10/11 and nothing works now.
Time to toss my Inspiron 3668?