At this age a dachshund should really only be walked for about 10-15 minutes, once a day. They say 5 minutes for every month old they are. They don't really need exercise as they are still growing but will require play time with toys and human interaction. Once the dog is fully grown he will be able to walk for as long as you are willing to take him, they are a hunting breed so enjoy long walks, with plenty of opportunities to go sniffing. However walking them too much when they are young can cause issues later on in life with their backs but it can also cause their feet to become out turned. I never understand peoples obsession with wanting to take their puppy especially a miniature dachshund out for walks straight away, I imagine it's for all the attention having a puppy can garner. It is a good idea at this age to try and socialise your pup with other dogs and different age humans but due to lockdown this will be difficult so taking to him to a park where other dogs will be (after he has had all of his vaccinations) is a good idea but you also need to be careful that the pup isn't running about too much and stick to the 15 minutes. The earlier you teach your dog to be off lead, the better. When they are puppies they are too fearful to run off from you but as they get older that fear leaves them so it is best to teach them as early as possible. That being said teaching your dog to be off leash only works if you are teaching them recall at the same time.Does a dog that small need a long walk?? I’m not a dog owner, so genuine question! Would just assume such a small dog would only need about 20 mins three times a day or something! Whereas they look like they are going on a trek with the poor little thing