Depends on the bread but for a standard bloomer, about 40-45 mins at 250.
Just doing a bit of reading, sourdough banneton loaves (what I'm aiming for) get done at 220 for an hour and sometimes a bit more at a lower temp after that, leaving to cool in oven etc.
I've struggled with getting really nice, thick crusts in the past. Using steam as well.
Is it just a case of leaving it in longer – like an hour?
Crust is always delicious straight out of the oven but quickly goes soft. Not bad, just soft.