I think this is more related to your card - this laptop is fairly old from the research I did on it (~2006-2008?) and it probably shipped with a Dell Wireless card, which Dell does a lot of the time on consumer models. I wouldn't be surprised if this is a chipset problem.
My advice would be to replace the factory wireless card and install a Intel card or Killer wireless card (Intel based, not QCA). A lot of Dell's first party wireless cards are not known for compatibility outside of the 1-2 versions of shipping Windows at the time the laptop was new. I ran into this issue with a DW1506 (AR9485 based, ath9k) on 10, so I had to replace the wireless card (long overdue anyway, due to the single band fail the 9k is known for). However, they work FANTASTIC in Linux.
Your laptop is old enough to be from the time period when Dell used Broadcom, so I would run "lspci -nn" and make sure you are right about this being an Atheros/QCA card. Judging from my research on Parts People a lot of the Dell branded cards are Broadcom.
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