Client connection issue on IPhone 16 Pro with safari

[chiragpetals]

Hey @endel,

I'm currently working on a Colyseus project and have run into an issue that seems specific to a particular device and browser combination. Users on the iPhone 16 Pro running iOS 26 with Safari are unable to join any Rooms except for the Lobby room when using the colyseus-client SDK.

Whenever they attempt to join a standard Room, they consistently receive a “seat reservation” error on the server side after some time. What's interesting is that this issue only occurs when using our client implementation. When the same devices access the Room through the Colyseus Playground from Safari, they can join rooms without any problem.

This suggests the issue might be isolated to how the client SDK is interacting with Safari on iOS 26 under these conditions, rather than a general compatibility problem with the server or the device itself. I wanted to bring this to your attention in case there are any known limitations, recent changes, or workarounds related to this configuration.

My configuration

1. I am running colyseus with the help of pm2 multiple instances with fork

• Pm2 config

  module.exports = {
    apps: [
      {
        port: 2567,
        name: 'app',
        script: 'src/index.js',
        watch: false,
        time: true,
        instances: 2,
        exec_mode: 'fork',
        env: {
          DEBUG: 'colyseus:errors',
          NODE_ENV: 'development',
          SELF_HOSTNAME: 'my-domain.com'
          MODE: 'multiple',
          COLYSEUS_SEAT_RESERVATION_TIME: 20,
          TZ: 'Etc/UTC',
        },
        ulimits: { nofile: 65536 },
        node_args: '--max-old-space-size=16384',
      },
    ],
  };

2. Nginx configuration

   error_page 502 /error.html;
   
   upstream colyseus_servers {
       server 127.0.0.1:2567;
       server 127.0.0.1:2568;
   }
   
   server {
       listen 80;
       server_name my-domain.com my-domain.com;
       return 301 https://$host$request_uri;
   }
   
   server {
       listen 80 default_server;
       listen 443 ssl;
   
       server_name my-domain.com my-domain.com;
   
       ssl_certificate /etc/letsencrypt/live/my-domain.com/fullchain.pem; # managed by Certbot
       ssl_certificate_key /etc/letsencrypt/live/my-domain.com/privkey.pem; # managed by Certbot
       include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
       ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
   
       location / {
           proxy_pass http://colyseus_servers/;
           proxy_http_version 1.1;
           proxy_set_header Host $host;
           proxy_read_timeout 86400s;
           proxy_send_timeout 86400s;
           include proxy_params;
           proxy_buffering off;
           proxy_set_header Upgrade $http_upgrade;
           proxy_set_header Connection 'upgrade';
           proxy_cache_bypass $http_upgrade;
           proxy_next_upstream error timeout http_502;
       }
   
       location ~ "^/(?<PORT>2[0-9]{3})/(.*)" {
           proxy_pass http://127.0.0.1:$PORT;
           proxy_http_version 1.1;
           proxy_set_header Upgrade $http_upgrade;
           proxy_set_header Connection 'upgrade';
           proxy_set_header Host $host;
           proxy_cache_bypass $http_upgrade;
           proxy_read_timeout 86400s;
           proxy_send_timeout 86400s;
           proxy_buffering off;
           proxy_next_upstream error timeout http_502;
           include proxy_params;
       }
   
       location /error.html {
           root /var/www/html;
           internal;
       }
   }

If there is something that i can do to debug this issue, feel free to guide me, i will share the logs with you.

[endel]

Hi @chiragpetals, I'm not aware of issues on recent iOS versions...

The "seat reservation" error when deploying on multiple instances generally occurs when the client is not getting directed to the correct node when trying to join the room. Are you exposing the publicAddress of each Node instance, so the client can connect directly to it?

When requesting to join a room, the first request can hit any Node process, which will respond with the room info (+ publicAddress). This room info is used to then establish a WebSocket connection directly to the node where the room found was spawned.

[chiragpetals]

Yes, i am exposing publicAddress and it is working fine on the same machine with Google Chrome, but this issue is specific to Safari on ios 26 running on Iphone 16 Pro, also, lobby is connecting fine on both Safari as well as 'Google Chrome`.

[chiragpetals]

Also, the response from the api for joinOrCreate is same for both Safari & Chrome

Url : https://my-domain.com/matchmake/joinOrCreate/dummyRoom
Response :

{
  "room": {
    "clients": 0, 
    "createdAt": "2025-11-25T17:42:18.461Z", 
    "maxClients": null, 
    "name": "dummyRoom", 
    "publicAddress": "my-domain.com/2568", 
    "processId": "TQ-pzUVtl", 
    "roomId": "6sUAJhQZq"
  }, 
  "sessionId": "z5pVjMDt3"
}

[endel]

I'd need to see the issue for myself to be able to understand what's going on. Feel free to send me the real URL of your project privately via email (endel [at] colyseus [dot] io) or Discord (endeld).

[endel]

We found out the issue is likely related to iCloud+ Private Relay bug on latest versions of Safari: https://forum.figma.com/report-a-problem-6/safari-maxos-26-sometimes-not-loading-websockets-45307