My book live not found from Mac Air

2TB mybook live working well with Mac Air, I pad 2 and Galaxy S3, now though after no changes works sometimes at full speed streaming to S3, not very often and very slow to I pad and my Mac Air cannot find it.
My Internet is 8meg works fine for anything else eg Netflix, hard resets do nothing and I’m not that computer savvy to start telling you about ip addresses unless someone can walk me through the process. Please some help !

Have you tried to reset all the devices on the network?