It seems it's related to CA certificate a connection authentication, according below

- https://electrum.readthedocs.io/en/latest/faq.html#i-might-run-my-own-server-are-client-server-connections-authenticated

I think the issue here is that your current Electrum server.
Have you tried to change your Electrum server first and test it again? That might be the reason why you got that error.