Can not reach Tahoe-LAFS

Hello,
i have installed Tahoe-LAFS on the box. In the Router i have opened the port 5678, https port 443 is also open for freedombox. If i try to reach my domain i get this:

SSL_ERROR_RX_RECORD_TOO_LONG

any suggestions?
Mikael


Debian GNU/Linux 10 (buster) and FreedomBox Version 19.1. (stable)
RaspberryPi 3b+ Firefox 68.01 manjaro Linux