This week I had a problem where wifi suddenly stopped working on my Lenovo ideapad 100 15iby running Elementary OS Freya. I don't know what happened, but suddenly the machine refused to work with any access points. It would say I was connected, and I would have an IP address from DHCP... but there was no actual connection working. Chrome would just complain there was no internet, for example.
I ended up having to rebuild the Realtek rtl8723be wifi driver from the source repository here: https://github.com/lwfinger/rtlwifi_new/ but actually that was not too bad, because the instructions are quite simple. I just had to follow this post which seemed to work fine for me. But I did need to disable the sleep feature of the driver, which is mentioned as an extra step in the instructions. Otherwise the connection would keep dropping and then prompting me for my wifi password all the time.
So that was a slightly annoying problem! But I am pleased to have it sorted out. As I'm writing this I'm downloading a 750Mb file to make sure it's all OK. I'm currently at 500Mb and all is fine, so hopefully that's a job well done.
I have also noticed that Elementary OS Loki is now released, but there is no upgrade route from Freya, so I need to find some free time to do a backup and clean install. Hopefully that will be a smooth process... maybe I'll try running it 'live' first, without installing, to make sure that things work beforehand. That's a job for another day.