Not used underfloor entrances, sure they work fine.
Regarding wasps, at the risk of sounding like a broken record, restrict your full colony entrances down all year round to around a bee space high and a couple of inches wide maximum. Keep colonies strong and wasps will simply be a non issue, promise.
Nucs or mini nucs need even smaller entrances. Bees robbing aren’t much better than wasps and they too need keeping out.
Bees really really don’t need a normal full width entrance and will struggle to defend it. So don’t oblige them to have one. Simples.
Regarding wasps, at the risk of sounding like a broken record, restrict your full colony entrances down all year round to around a bee space high and a couple of inches wide maximum. Keep colonies strong and wasps will simply be a non issue, promise.
Nucs or mini nucs need even smaller entrances. Bees robbing aren’t much better than wasps and they too need keeping out.
Bees really really don’t need a normal full width entrance and will struggle to defend it. So don’t oblige them to have one. Simples.