Looking for answer to water heater sme

[KSPlumbingIssue]

At our wits end. Remodeled a farm house in 2020, installed the water heater and due to appliances being backordered couldn't move in until Nov. of that year. After a hot shower we noticed a terrible smell. We had the lines smoked, venting tested, used a camera on the lines, all from a local professional plumber. The water has never had a smell, and only after a hot shower do we smell it.
We also changed the anode rod, drained and flushed with peroxide.
We finally gave up and bought another water heater. It was fine for a week and tonight we are smelling it on the new hot water heater after a hot shower.
Im sick. $2,000 we have invested in hot water heaters and still have the same problem. Desperate for a new solution!

 

[Timmy D]

You need to narrow down your search area.

Does it smell on a cold shower?
Does the hot water smell through other outlets?
Does it smell direct out of the water heater?
Can you run a garden hose connected to a cold supply outside the problem shower and run it in to the shower drain? Does it smell?
Can you do the above but with hot water?
Does the smell stop/disappear once shower is over? How long?
How you checked basin trap after shower to ensure it hasn’t been sucked dry?

You need to think like this and test/record results. Including times between test start and smell being present.