Thanks for the messages everyone. Yes he defenitely has ALOT of toys to keep him busy during the day, but still he would rather opt for my furniture!
I don't feel that a playpen is maybe a good idea, just because we already restrict him from going outside during the day until we get home, so it feels cruel to me to put him in a small play pen

And we do not have something like a daycare here...
We are gone from 8 in the morning and my husband gets home usually around 3h in the afternoon.
Asterix is currently enrolled at a dog training school as well. Our trainer said that his behaviour is related to attention seeking. He knows he will get attention if he does something like this as we would reprimand him (but he have stopped doing this a while ago). But we overflood him with attention, he is really a spoiled little brat! Our trainer suggested that we rub citronella or tobasco on the items that he likes to chew on.
When he has destroyed something inside the house, I usually do not give any attention to that, I would just leave it and clean up later when he does not see me.
Maybe I just really have a spoiled little brat!