OK.
I will give DAWN a try.
I installed it on both routers.
On RT3200 the radio did not come up.
Logread said (and another Line, which I did not capture):
daemon.err hostapd: Line 79: unknown configuration item 'bss_transition'
Found a post here:
solved-unknown-configuration-item-bss-transition
Installing wpad-wolfssl ended with
Required dependency package libwolfssl5.3.0.ee39414e is not available in any repository.
So I replaced wpad-basic-wolfssl with wpad-openssl.
Dawn is now up and running.
I'll see, how it works.