Using Grafana with SSL on Debian LAMP server

I run Grafana on a Debian server that is primarily used for our groupware solution.

On this server I have SSL set up for Apache - with LetsEncrypt. This works fine - and LetsEncrypt is automatically updated with a cron job etc.

  1. Can I use the same LetsEncrypt setup for accessing Grafana via SSL on this server?

  2. On the same server I can not use Grafana at all with http: on Firefox - but Chrome & IE works :

Example: works fine in Chrome and IE.

If i try with Firefox, the site is automatically redirected to and Firefox says “SSL_ERROR_RX_RECORD_TOO_LONG”

Thanks for all help!