After installing Elementary OS, there was no wifi adapter. I followed these instructions and it worked, however, my wifi was extremely slow compared to other devices using the same network.
The fix for this problem was:
sudo modprobe -r rtl8723de && sleep 5 && sudo modprobe rtl8723de ant_sel=2
After running that command, my wifi becomes normal again, however, the fix is not permanent. Every time I boot up the PC, I need to run that command to not have slow wifi. I would like to make this solution permanent.