Hello,
I am trying to use bitwarden client on my phone with my self-hosted vaultwarden server behind an nginx reverse proxy.
To secure the server I followed the instructions here to create my own PKI. In my desktop browser I added the root CA and I can access vaultwarden without a problem and view my own certificate.

I am now trying to do the same with my phone but I am facing an error : Exception message: Connection failure when I input my email. I suppose that at least one of the problems is that I don't have my internal PKI's root CA installed on my phone.

I am now trying to install the root CA (Settings -> Security -> More security settings -> Encryption & credentials -> Install a certificate -> CA certificate) but it fails silently. I searched the logs (Settings -> System -> View logs) for root-ca.crt which is the cert name and the logs that I got back are found here

I have been trying to install the root-ca.crt file. Could it be that GrapheneOS is expecting a .der or a .pem format?
Even if I did install the certificate should I expect it to work? I have seen a few posts suggesting that maybe apps only trust system trusted credentials.
Can someone recommend a step by step way to actually have the android bitwarden client be able to contact the vaultwarden server.
A workaround could be to use a Let's Encrypt certificate.
Thanks in advance