nginx 配置问题求解答

问题描述：a 服务器的 nginx 服务会将 /aisp/approval/ 路径的请求转发给我，我收到请求后根据user-agent判断是移动端还是 pc 端请求，如果为移动端的，则去当前服务器的/home/centos/web/h5目录下响应对应的静态文件。如果是/aisp/approval/api/路径下的请求则请求后端服务，当前的配置：

server {
        listen 9999;
        server_name localhost;

        location /aisp/approval/ {
            if ($is_mobile = 0) {
                rewrite ^/aisp/approval/(.*)$ https://b.com/$1 permanent;
            }
            alias /home/centos/web/h5/;
            try_files $uri $uri/ /index.html;
        }

        location  /aisp/approval/api/ {
            limit_conn perip 1000;
            proxy_pass http://10.156.166.23:9088/;
            proxy_redirect off;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $host;
            client_max_body_size 600M;
            client_body_buffer_size 512k;
        }
    }

现在的问题是通过移动端请求a.com/aisp/approval/workOrder/orderHandlerDetails,error.log 会报：

open() "/usr/local/nginx/html/home/centos/supervision/web/h5/index.html" failed (2: No such file or directory)

/usr/local/nginx/html 是我 nginx 的安装目录，我要如何配置才能在请求 a.com/aisp/approval/workOrder/时响应/home/centos/supervision/web/h5/目录下的 index.html