Nginx Location Redirect

Question

I'm sorry for the beginner question but I've spent a long time trying to get this to work properly with no luck.

I have a location block to redirect https://my.domain.com/foo to https://192.168.1.25, which hosts a webapp. When you get to the webapp, the webapp automatically redirects you to https://192.168.1.25/login to log in. When typing in the local IP (https://192.168.1.25) this redirect happens as expected.

When I visit https://my.domain.com/foo, it redirects to https://my.domain.com/login instead of https://my.domain.com/foo/login and I cannot figure out why. This leads to a 404 error.

Here is the relevant section of my nginx.conf file:

    server {
        listen       80;
        server_name  my.domain.com;
        return 301 https://$host$request_uri;
    }

    server {
        listen       443 ssl;
        server_name  my.domain.com;
        include ssl_my_domain.conf;

        location /foo/ {
            proxy_pass https://192.168.1.25/;
        }
}

As far as I'm aware, setting trailing slashes in the location block (/foo/ and 192.168.1.25/) should work (as in the responses in Nginx Redirect via Proxy, Rewrite and Preserve URL and elsewhere) but it's just not redirecting properly.

Any help is appreciated.