Please tell me how to set SSL with GCP Load balancer

Hi,

I’m using a GCP load balancer.
It has the following configuration.
Cloudflare (encryption mode) <=> (GCP load balancer) <=> Cloud Run

So far, the GCP load balancer SSL certificate has been installed and used with the GCP SSL certificate.
Cloudflare’s DNS (record hoge.fuga.example.com) settings were used only for DNS.
This setting works fine.

However, if I change Cloudflare’s DNS settings (record hoge.fuga.example.com) to a proxy, my browser will display “ERR_SSL_VERSION_OR_CIPHER_MISMATCH”.

Also, the error does not change even if you use the SSL certificate of the GCP load balancer and the SSL certificate (origin certificate) issued by Cloudflare together.

how cloudflare <=> GCP loadbalancer Is it possible to communicate normally by setting SSL of GCP load balancer?

Is it impossible to get a Cloudflare plan for free?