This document mainly introduces the solution to the problem that you cannot log in to the CVM instance after purchasing it, helping you locate and solve the problem.
Main Cause of Fault
The following figure shows the main reasons for being unable to connect to a CVM instance and their occurrence probability. If you are unable to connect to the instance, troubleshoot based on the following possible reasons.
Troubleshooting Steps
Confirming the Instance type
First, you need to know whether the instance type you purchased is a Windows system instance or a Linux system instance. Secondly, different instance types may have different reasons for not being able to log in to CVM. You can refer to the following documents to locate and solve the problem based on the instance type you purchased:
Port Problem
Fault Symptoms
The remote connection to the port failed.
Solution
This may be caused by the remote access port being a non-default port or the port settings being inconsistent.
See Port Problem Resulting in Failure to Remote Connect for details.
High CPU/Memory Usage Issue
Fault Symptoms
When you use the CVM, problems such as inability to log in, slowdown of service speed, and sudden disconnection of instances occur.
Solution
There may be a problem of excessive CPU or memory usage. Check the resource usage.
- For Windows CVMs, see Unable to Log in Due to High CPU and Memory Usage in Windows System.
- For Linux CVMs, see Unable to Log in Due to High CPU and Memory Usage in Linux System.
Public Network Isolation Issue
Fault Symptoms
The CVM was partially isolated due to a violation or risk event.
Solution
For details, see Public network is Isolated and Cannot be Connected Remotely.
High Usage of Public Network Bandwidth Issue
Fault Symptoms
The bandwidth is full or high, resulting in a login failure.
Solution
For details, see Unable to Log in Due to High Public Network Bandwidth Usage.
Unable to Use Password After Associating the Key
Fault Symptoms
Once the CVM is associated with a key, logging in via password will be disabled. Please ensure that the firewall settings and IP configuration of the network interface are accurate.
Solution
After the CVM is associated with a key, the CVM SSH service will disable username and password login by default. Please use the key to log in to the server.
Unable to Log in with Password in Xshell
Fault Symptoms
When you log in using Xshell, you cannot use a password to log in to the CVM.
Solution
You have selected the key login method when installing the system. For how to use the key, see SSH key operation. If you need to log in with a password, you can select password login when reinstalling the system, or log in to the computer and modify the sshd configuration file.
Other Common Causes of Login Issues
If the cause of the problem cannot be located through the above directions, or the following types of error messages are directly returned when you log in to the CVM, you can refer to the following solutions.
Windows Instances
- Windows Instance: No permission to Log in via Remote Desktop Services
- Windows Instance: Mac Remote Log-in Exception
- Windows Instance: An Authentication Error Occurred
- Windows Instance: Network Level Authentication Required
- Windows Instance: Remote Desktop Cannot Connect to the Remote Computer
Linux Instances
Linux Instance: High CPU and Memory Usage Causes Login Failure
Subsequent Operations
If the above steps still cannot solve the problem of being unable to log in remotely, you can save the relevant logs and self-test results and feedback them to the maintenance engineer.