Nginx HTTP2 IOS 11 not working

i have problems with HTTP2 protocol on my NGINX server, this is my configuration

listen 443 ssl http2;
server_name adomain.com;
root /var/www/project;

limit_req   zone=one  burst=60 nodelay;

add_header Strict-Transport-Security "max-age=2592000; includeSubdomains;" always;
ssl_certificate     /etc/letsencrypt/live/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/privkey.pem;
ssl_protocols   TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:ECDHE-RSA-AES128-GCM-SHA256:AES256+EECDH:DHE-RSA-AES128-GCM-SHA256:AES256+EDH:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";
ssl_prefer_server_ciphers on;
ssl_session_cache   shared:SSL:10m;
ssl_session_timeout 10m;
ssl_dhparam /etc/nginx/ssl/dhparam.pem;

resolver 8.8.8.8;
ssl_stapling on;
ssl_stapling_verify on;

keepalive_timeout   70;

I can’t see the error on my iOS device (safari 11), it's very strange the webpage is a SPA ( angular ) that app makes requests to an API, the apps loads over HTTP2 but when the app has to make requests to the API it fails, disabling HTTP2 from the listen makes everything works as espected

The ciphers for both servers frontend/backend are the same

In Chrome/Firefox/IE works fine, i don't know what is wrong with Safari or my server config

The error.log and adomain-error.log are empty when Safari fails

Nginx Version

nginx version: nginx/1.12.2
built by gcc 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) 
built with OpenSSL 1.0.2k-fips  26 Jan 2017
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib64/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC' --with-ld-opt='-Wl,-z,relro -Wl,-z,now -pie'

UPDATE

The console on my IPhone says Protocol error so i'm pretty sure that it's an error of the IOS 11

UPDATE 2

I have found this post

https://www.nginx.com/blog/http2-theory-and-practice-in-nginx-stable-13/

It explains that if you support TLSv < 1.2 you will end up in a PROTOCOL ERROR , leaving in my server config just TLSv1.2 makes the app works again, but it's buggy , some requests will fail … that's beyond my comprehension, once again in Chrome/Firefox it's working but in my mobile safari it doesn't

UPDATE 3 [2019/02/28]

There was a bug on our NGINX config for the OPTIONS Method of a CORS request causing duplicated Content-Length and Content-Type headers to be responded, after we solve that the app started working fine in HTTP/2, we also changed the status of the OPTIONS response from 200 to 204