Basically, once I started my computer it had no Internet. After some troubleshooting I found the WiFi interface name randomly changed from wlan0 to wlp1s0, so I started the WiFi card, wpa_supplicant and dhcpcd manually and Internet came back, but with random disconnections. Then, after I did some stuff on the computer, I changed the systemd units to reflect the new name and restarted, but for some reason wpa_supplicant was unable to start properly (after some research I found the /run/wpa_supplicant/wlp1s0 file wasn't deleted after reboot). I tried using iwd instead of wpa_supplicant and also tried changing the interface name to what it was before the problem happened (and more stuff from the wiki), but nothing changed. As a last attempt to solve the problem by myself I changed Network Manager to netctl and that finally solved both problems.

Package versions:
- networkmanager 1.32.8-1
- wpa_supplicant 2:2.9-8
- dhcpcd 9.4.0-1
- iwd 1.16-1
- netctl 1.25-1
- linux-lts 5.10.56-1
- linux-lts-headers 5.10.56-1 (the two last may be relevant)

Hardware (may be relevant):
-WiFi card: Qualcomm Atheros AR9485 (kernel module ath9k)

PS: My networking knowledge is pretty elemental. Also, I didn't saw this problem in the upstream forums or in the Arch's ones