Outbound http request on specific port

Serilog itself isn’t blocking anything here. This is almost always a network issue. Port 5341 is Seq’s default, but many hosting providers and firewalls block outbound traffic on non standard ports. That’s why 80 and 443 work more reliably. You have a few options. You can expose Seq behind a reverse proxy and forward it through port 80 or 443. That’s the most common fix. Or you can open port 5341 explicitly in your firewall and hosting rules, both inbound on the Seq server and outbound from the app environment. If this is cloud hosted, check security groups or network policies. From Serilog’s side, no extra config is needed once the port is reachable.