Checking the Dell website it appears there have been issues with the standard card and it’s not clear which card they used during the life of this machine
The support recommend a replacement
https://www.dell.com/community/XPS-Desktops/Dell-XPS-8900-Upgrade-WiFi-Card/td-p/7367214
But this needs you to take the box apart to replace … if you feel up to it and capable … not everyone wants to do this
Other option is to buy a separate dongle WiFi key like a sub memory stick
https://www.amazon.com/s?k=Usb+Wi-Fi+key&ref=nb_sb_noss
Please note I don’t work for Amazon and in no way do I get anything from them it’s just to give you ideas of what and where. You may find the same at a local computer shop (with free advice) or a large supermarket offering computer bits or a specialist supplier
To check your existing card
Although the guide is for Ubuntu the info works on mint
Go into terminal
Type
sudo lshw -C network
This will give you more details which may help solve your issues