TLS: failed to verify certificate: x509: cannot validate certificate for <IP> because it doesn't contain any IP SANs

Question

Background:

1. I have a Prometheus process and a Prometheus-PushGateway process in the customer environment
2. I have a go process which use Pusher.Push() function to push some customized metrics to the PushGateway and then PushGateway convey it to the Prometheus.
3. I don't know how the customer deploy the Prometheus-PushGateway, but they gave me a https's address and I can use curl command to visit like:

curl -H 'Host: upfs-pgw-nm04-a800.glm.ai' -k https://<IP>:9443/metrics

Here it use -k to avoid the permission issue, if cancel it the problem'll appear just like the first problem described below, the condition without -k:

Part of the code related to the Push fucntion:

        // Ignoring contextual environment
    pusher := push.New(pushgatewayAddr, jobName).Collector(reg)

    if err := pusher.Push(); err != nil {
        uflog.ERROR("reportCapacityToPushgateway error: " + err.Error())
        return err
    }

The API adress: https://pkg.go.dev/github.com/prometheus/client_golang/prometheus/push#Pusher.Push

Problem:

1. Now I encounter a problem during customer testing, see the pic below:

2. I know the Push-Golang package have a HTTPdoer type and guess it can help to skip the client verify from PushGateway but I don't know how to do it ? In other words, how can I use this golang package to Push without the Permission verification ?

3. I know the Prometheus-PushGateway has a --web.config.file to enable TLS or authentication but I don't know how to config it avoid this problem though I have reviewed this doc from the help info ? https://github.com/prometheus/exporter-toolkit/blob/master/docs/web-configuration.md

I haven't tried some ways and I expect that there is a way to solve this permission problem, and I hope that best solution is to be on the go-process rather then the Prometheus-PushGateway as customers have deployed the Prometheus and PushGateway, it's not convenient to ask them to do something more. I would be extremely grateful if you can help me solve this problem thx !