First make sure your clock is set correct.
Also check the log for any issues.

Many sites has gone down, and are not online anymore that are linked to all over the place.

Then try some of the sites that are hosted by big providers with the most amount of uptime.

Some examples are: 

facebook https://facebookcorewwwi.onion

DuckDuckGo 
https://3g2upl4pq6kufc4m.onion/

If these sites work, then I'd say that the other sites you are trying is simply not online.