Frequent disconnections from US servers are a common problem encountered by many users, from beginners to those with some experience. The symptoms can vary: some experience frequent SSH disconnections requiring repeated reconnections; others find their websites intermittently accessible, sometimes working and sometimes not; still others find the server itself running, but inaccessible from the external network. Without systematic analysis, these problems can easily lead to a vicious cycle of "restart—slowly working—disconnecting again." In reality, the root causes of frequent US server disconnections usually lie in network, connection, configuration, resource usage, and the external environment. With a clear approach, even beginners can pinpoint and resolve the issue step by step.

　　First, it's crucial to understand that a "disconnection" doesn't necessarily mean the server is down. Often, the server itself is functioning normally, but your current network connection is unstable. Therefore, the first step is to check the server status. Log in to your cloud provider's backend and check if the instance is running, suspended, frozen, or restricted due to unpaid fees or abnormal traffic. Some US servers may experience temporary restrictions on external network access when experiencing abnormal traffic, being attacked, or triggering risk control rules within a short period, but the console will still show "Running". If there are any alerts or notifications in the background, be sure to check them first.

　　After confirming that the server is running normally, you need to distinguish between a "global outage" and a "partial network outage". The simplest method is to test access in different network environments. For example, you can try accessing it once with your local broadband and then again with your mobile hotspot, or have a friend in another region test it for you. If you find that some networks are accessible normally while others are almost inaccessible, the problem is most likely not with the server itself, but with the quality of the cross-border line. This is very common when accessing US servers from within China, especially during peak evening hours, when ordinary international lines are prone to severe packet loss and instability.

　　In this case, the solution is not to repeatedly reinstall the system, but to improve the network path. The most direct way is to choose a US server with better line quality, such as CN2 GIA, premium back-to-China lines, or multi-line BGP optimized lines. Many users initially choose standard lines to save costs, only to find themselves experiencing "almost daily disconnections" once their businesses are up and running. The root cause is often the limited capacity of the existing lines. If you don't want to replace your server immediately, you can use relays or acceleration nodes to make the connection path more stable, which is especially useful for operations and remote management.

　　If you find that your server frequently disconnects from SSH regardless of the network used, you should start checking for internal server issues. One of the most common causes is insufficient server resources. For example, insufficient memory can cause the system to frequently trigger OOM (Out of Memory) mechanisms under high load, directly killing processes and potentially even affecting the SSH service. You can check the current resource usage on your server:

top

　　or：

free -m

　　If you find your memory is almost full and your CPU is at 100% for extended periods, then a disconnection is likely due to your system "underpowered." In this case, the most effective solution isn't "optimizing SSH," but rather upgrading your server configuration or disabling unnecessary services to reduce resource consumption. Many beginners running databases, websites, web crawlers, and scheduled tasks on low-spec servers frequently experience resource exhaustion.

　　Another easily overlooked reason is running out of disk space. When the disk is full, system logs and temporary files cannot be written correctly, many services will malfunction, and SSH may become unstable. You can check disk usage using the following command:

df -h

　　If a partition is found to be at 100% capacity, you need to promptly clean up useless files and logs, or expand the disk space. This type of problem is often not a sudden "disconnection," but rather a gradual slowdown of the server, eventually leading to highly unstable connections.

　　The next key area to check is the firewall and security policies. Some users have configured firewall rules on the server, or installed security software or anti-brute-force tools. If these rules are improperly configured, legitimate IPs may be treated as abnormal activity and blocked. For example, if you fail to log in to SSH multiple times in a short period, the system may automatically block your IP, making you feel like the server is constantly disconnecting. You can try connecting again by changing your IP address, or log in to the server via the console to check the firewall logs and blocking rules.

　　In Linux systems, you also need to confirm that the SSH service itself is running stably. You can check the SSH service status:

systemctl status sshd

　　If the SSH service frequently restarts or exits abnormally, you need to check the logs, usually in `/var/log/secure` or `/var/log/auth.log`. Configuration file errors, port conflicts, and permission issues can all cause SSH instability. Some beginners modify SSH configurations for security but forget to restart the service or enter incorrect parameters, resulting in intermittent service.

　　Additionally, frequent disconnections from US servers have another real but often underestimated reason: attack traffic. US IPs exposed to the public internet are easily scanned, subjected to brute-force attacks, and even small-scale DDoS attacks. Even small-scale attacks can saturate your bandwidth or connection count, causing instability in normal access. You can easily check the current connection status on the server:

netstat -an | wc -l

　　An unusually high number of connections should raise a red flag. In this case, consider enabling basic protection, restricting SSH login IPs, changing the default port, or enabling protection services in the cloud provider's backend. Many servers that "mysteriously disconnect" are actually slowed down by attacks.

　　Another scenario is that the disconnection only occurs on SSH, but website access remains normal. In this case, consider using an SSH keep-alive mechanism to prevent disconnections due to network fluctuations. For example, enable heartbeats in your local SSH client configuration.

ServerAliveInterval 60
ServerAliveCountMax 5

　　This can alleviate the problem of "disconnection after prolonged inactivity" to some extent. However, it's important to note that this only improves the user experience and does not solve the underlying network instability.

　　If you've already checked the network, resources, firewall, and SSH service, and the problem persists, then the last crucial step is to make good use of your cloud provider's support. Don't underestimate the value of official technical support; they can help you troubleshoot from a deeper level, examining network conditions, host machine status, and routing anomalies. Sometimes the problem isn't with your server, but with a data center node or upstream network; only the service provider can handle these types of issues.

　　Overall, frequent server disconnections in the US are almost never due to a "single cause," but rather the result of multiple factors. A common mistake beginners make is focusing on one point repeatedly, such as constantly restarting the server or reinstalling the system, while ignoring network lines, resource bottlenecks, and the security environment. The correct approach is to first distinguish between network and server issues, and then troubleshoot layer by layer from the outside in. With a clear logic, even if it's your first time encountering this situation, you can completely control the problem and even improve your understanding of servers and networks in the process. This is also an essential step for many people to go from "a novice using a server" to "truly knowing how to use a server".