x.x.x.x.sslip.io is the public ip to myu nginx load balancer

not 100% sure, but did you follow these additional steps? https://rancher.com/docs/rancher/v2.5/en/installation/install-rancher-on-k8s/chart-options/#:~:text=External%20TLS%20Termination,-We%20recommend%20configuring&text=Use%20the%20%2D%2Dset%20tls,cluster%20will%20not%20be%20encrypted.