Weimaraners

Lots of pups have anxiety issues when left alone, because their security came from their mother and litter mates.  When you became owner, you became the center of the world, and so being unhappy at your being gone is perfectly normal, particularly for the age, and not unique to this breed.  Even if you have the pup crated when you are away, I would tend to leave your other dog as a companion.  And try being away for just short little things-5-15 minutes and see how well he tolerates that.  You could even crate him while you are in the house elsewhere doing some other chores, and see how he fares-how long it takes him to settle and be quiet again.  I wouldn't let him out of the crate while he is in full howl, because that might give the notion that you are rewarding the howling behavior, but rather wait until he is settled to let him free. ( sometimes that means just a few quiet breaths between yodels for a puppy), but you want to reinforce the quiet waiting behaviors.  Make sure he has toys, maybe a blanket or rug that smells like you (expect with a puppy that it may get shredded and chewed)  And as the pup gets older, the frantic separation thing should ease off.  Also don't be really rowdy with your greetings.  Very quiet and calm greetings  and leaving will further the idea that it is no big deal and you will be back to see to their needs