Why isn't my computer connecting to wifi?

It sounds like you have issues with the card or the networks you’re connecting to deprioritize 2.4GHz over 5 GHz. Not unusual since 2.4 is mostly a noisy mess (because nobody checks the bands in their area with a spectrum analyzer like you should be doing if you're a responsible human who uses it, and picks a non-congested band) these days and is only good for wall transmission.

Sadly, the only good long term solution to fix these laptops is a new wireless card (ath10k Atheros or Intel AC). It’s quite a job and you will need to change drivers out but once you replace the original Ath9k card the issue is permanently fixed and will behave like a whole different computer on WiFi. Granted it won’t be as dramatic on a netbook, but when I replaced my DW 1506 (Ath9k-based rebrand/AR5B125, AR9485 chipset) in my old Dell it was a completely different machine over WiFi. The newer ones are just as good (if not better) but you’re limited to the 7260AC since the later chipsets from the Intel AC line are M.2 NGFF only.

Acer Aspire One D270-1865 RAM Replacement