Network is unreachable or no route issue

Hello everyone,

I made a turn based card game and I have a problem with connection.
I run my server in digitalocean servers (ubuntu) and I am getting connection issue when user tried AuthenticateDeviceAsync and client throw exception like this :

Non-fatal Exception:
java.lang.Exception SocketException : Network is unreachable or SocketException : No route to host

It is not reproducible, what’s wrong at my implementation?

My connection flow is;
Firstly:
client = new Client(“http”, ipNumber, 7350, hashCode);

Secondly:
session = await client.AuthenticateDeviceAsync(SystemInfo.deviceUniqueIdentifier);

After then I continue other stuff.
This issue not happened every user, sometimes and someone getting this issue.
Btw I experienced this issue at my local network. Not only digitalocean servers.

Thanks.