Give a Dachshund a burrow, not a front-row seat
A Dachshund was bred to go to ground after badgers, so when fireworks start, his instinct is to dig into the darkest, tightest space he can find. Work with that instinct instead of fighting it. Build a proper burrow in an interior room away from windows: a low crate or a corner piled with blankets he can tunnel under, with one worn jumper of yours worked into the bedding. Close the curtains, switch on a television or radio at ordinary volume, and let him disappear. A Dachshund who has burrowed and gone quiet is coping, not sulking, so resist lifting him out for reassurance cuddles that expose him to the noise again.
Protect that long back while he is frightened
Panic changes how a Dachshund moves. A dog who normally waits to be lifted may suddenly launch himself off a sofa arm, scramble up stairs he should not climb, or twist sharply in your arms when a rocket cracks overhead. Those jumps and twists are exactly what his long spine handles badly. Block the stairs with a gate before dark, lift him with both hands supporting his chest and rear if he must be moved, and keep him off high furniture for the evening. If children are visiting, settle them away from his burrow, because small hands pulling back blankets to check on him will undo the one place he feels hidden.
Toileting, doors and the low-level escape route
Do the last garden trip in daylight, on a lead, even in your own fenced garden. A frightened Dachshund runs low and fast, and the gap under a gate that his deep chest normally squeezes through slowly becomes no obstacle at all at a sprint. After that trip, he stays in, with a washable pad near the back door if the night runs long. Check that his collar sits snug enough that it cannot ride over his ears when he backs away from a bang, and keep hallway doors shut so a dash through opening front doors, as guests arrive or leave, ends in another room rather than on the street.
If he panics, hides or will not settle
Some Dachshunds shake, pant and dig at carpet for the whole display, and that miserable evening on its own is not an emergency. Watch instead for a dog who will not take water the next morning, who yelps when his back is touched, who drags or wobbles on his back legs, or who has hurt himself scrambling over furniture. Back-leg wobbling or pain after a night of frantic jumping deserves a prompt veterinary call, because spinal problems in this breed worsen when they are left. Note where he chose to hide, what time the shaking eased and whether the burrow helped, so next time you can set up the winning arrangement before the first bang rather than improvising during it.
A frightened Dachshund who does get past you is hard to spot in the dark, low to the ground and quick under hedges, so KinsLe's Lost Pet Alert System lets you warn nearby members at once and lets whoever finds him reach you straight away.