Network speed of a simple application server does not match the expected network bandwidth of the server - Simple Application Server

When a website or application hosted on a Simple Application Server loads slower than expected, the actual network speed may not match the bandwidth you specified. Use this guide to identify the cause and resolve the issue.

Causes and solutions

Before working through each cause, check the Simple Application Server console for billing alerts or service notices. An overdue payment (cause 4) is the fastest to rule out and the quickest to fix.

Cause	Key symptom	Solution
Cross-border network latency	Slow access from the Chinese mainland to a server in China (Hong Kong)	Test and migrate to a Chinese mainland region
Bandwidth exhaustion	Outbound bandwidth near 100% in monitoring	Upgrade bandwidth or stop abnormal processes
Unstable local network	Other websites also load slowly	Run a network path test
Overdue payments	Server became slow or unreachable	Renew the server

Cross-border network latency

Symptom: A client in the Chinese mainland experiences slow or failed connections to a Simple Application Server in the China (Hong Kong) region. Clients outside the Chinese mainland connect normally.

Cause: Cross-border interconnection between the Chinese mainland and regions outside the Chinese mainland depends on Internet service provider (ISP) routing. Traceroute analysis may reveal an abnormal node at the egress of the cross-border link. Alibaba Cloud reports such faults to the ISP, but resolution depends on the ISP.

Solution:

Test whether other servers outside the Chinese mainland also experience slow access from the Chinese mainland. This confirms whether the issue is isolated to one server or affects the entire cross-border route.
If the issue affects multiple servers and impacts your business, migrate the server to a region in the Chinese mainland.

For more information about cross-border connection issues, see A timeout error occurs when I connect to a simple application server deployed outside the Chinese mainland.

Bandwidth exhaustion

Symptom: The server responds slowly or stops responding. Monitoring shows outbound bandwidth usage at or near 100%.

Cause: High outbound traffic saturates the server's bandwidth. This typically has one of two sources:

High legitimate traffic: The server receives a large volume of requests due to business growth.
Malicious traffic: The server is under a network attack, such as a DDoS attack.

To confirm, go to the server's Monitoring page in the Simple Application Server console and check the Outbound bandwidth chart. If usage is sustained at or near 100%, bandwidth exhaustion is the cause.

Solution:

For high legitimate traffic: Upgrade the server to increase bandwidth. For more information, see Upgrade a simple application server.
For malicious traffic: Log in to the server and run the following checks to identify processes driving abnormal traffic:
- Run netstat -an or ss -tulnp to list active connections and find processes with an unusually high connection count.
- Run top or htop to find processes consuming abnormal CPU or network resources.
- Run crontab -l to check for unfamiliar or recently added scheduled tasks.
After identifying abnormal processes, stop them and remove any associated scheduled tasks.

Unstable local network

Symptom: Slow speed is not specific to the Simple Application Server—other websites and services also load slowly from the same on-premises device.

Cause: The on-premises device has an unstable network connection, causing packet loss or high latency along the route to the server.

Solution: Run a network path test to pinpoint where packet loss or high latency occurs. For more information, see Test network paths when packet loss or connection failures occur after the ping command is run.

Overdue payments

Symptom: The server was previously accessible but became slow or unreachable.

Cause: An overdue payment for the Simple Application Server restricts server access.

Solution: Renew the server to restore access. For more information, see the Renew a simple application server section of the "Upgrade and renew a simple application server" topic.