My HAC does not like my SSL certificate

Hello,
I’ve just finished to install an HA server. If I connect to https://sk4mc.hopto.org:8123 from a browser (any browser) it works. But if I try to do the same with a mobile device using HAC

Could someone tell me where is the problem?

HAC 2.4.1-full
Home Assistant 0.116.0.dev20200923

you need a valid SSL cert for the app to work, if you have to accept a SSL cert in a browser then it wont work.