IdentityServer4 SSL problem, I can't make HTTPS request

Question

I have some microservices. One microservice which is IdentityServer runs over HTTPS, I also have a second microservice which is a protected API and it uses HTTP(I can’t change it)

This is protected API(Client credentials flow)

services.AddAuthentication(IdentityServerAuthenticationDefaults.AuthenticationScheme)
                .AddIdentityServerAuthentication(options =>
                {
                    options.Authority = "https://localhost:5001";
                    options.RequireHttpsMetadata = false;
                    options.ApiName = "NotifyAPI";
                    options.ApiSecret = "api_secret";
                });

It can't make a https request from http

Error connecting to https://localhost:5001/.well-known/openid-configuration. The SSL connection could not be established, see inner exception.

This method works, but I can't change HttpClientHandler in the Authentication configuration(Startup.cs)

using (var httpClientHandler = new HttpClientHandler())
            {

                httpClientHandler.ServerCertificateCustomValidationCallback = (message, cert, chain, errors) =>
                {
                    return true;
                };
                using (var client = new HttpClient(httpClientHandler))
                {

                    var response = await client.GetAsync("https://localhost:5001/.well-known/openid-configuration");
                    return response;

                }
            }