There's some kind of nasty tasting spray to get dogs from chewing on things, but at your puppies age, you'd have to spray literally everything. So that's not ideal. When my dog went through this phase, we just had to make sure all chewable clothes, stuffed animals, cords you name it, off the floor or in reach of the dog. Unfortunately it's not always easy because you can't protect everything. My dad tried to teach my dog with negative reinforcement by hitting her , but eventually she didn't really have the problem, so I think it was just a phase.

Something I just thought of... What if you hid treats around the house (or the room if you enclose the dog in 1 room) while you are away. That way the dog can have fun getting to the treats so thats the focus instead of chewing on everything else. It probably won't work for being away for a long time, but it could work..