I also have trouble connecting after sleep on my MacBook, but I usually just turn off the Wi-fi and turn it back on after it wakes up if I run into the problem and it works. It's a quirky issue and I've heard quite a few people ask about it on here.
Also about the signal being too far away, that's possible. I used to get like a single bar on my iPhone and it would pick it up as available and refuse to connect unless I was a bit closer.