Failed to update plugins due to network connection issues – Support | JetBrains

Problem

When attempting to update plugins in CLion by selecting Check for update, the operation fails with the following error message:

Connection failed (Connection reset). Please check network connection and try again.

No updates appear even after reinstalling CLion.

Cause

The issue is related to the network connection. Concurrent connection requests to the JetBrains plugin marketplace are being partially dropped. This was confirmed through testing with curl commands, which demonstrated that some requests would succeed while others would fail under the normal network setup. Upon further testing, it was identified that these drops likely occurred due to the home router or ISP settings limiting bursts of simultaneous connections.

Resolution

Confirm whether you are running any security software (e.g., firewalls, antivirus) that might interfere with the connection.
Check if a proxy or VPN are being used.
Verify the IDE proxy settings are correctly configured via Settings (⌘ + , or Ctrl + Alt + S) > Appearance & Behavior > System Settings > HTTP Proxy.
Test connectivity by directly accessing this file in your browser to ensure access is possible.

Run the following diagnostic commands to analyze the connection behavior:

for i in $(seq 1 20); do (curl -4 -s -o /dev/null -w "%{http_code} " https://plugins.jetbrains.com/files/brokenPlugins.json &); done; wait; echo

curl -6 -v https://plugins.jetbrains.com/files/brokenPlugins.json

Try connecting to a different network, such as a mobile hotspot. If the issue does not persist with the alternate network, this confirms the problem lies with your primary network setup.
Reboot your router or modem and check its admin settings for any configurations or limits affecting simultaneous connection attempts.
If using IPoE (OCN Virtual Connect) with your ISP, consider switching to PPPoE. This resolved the issue for the user in this case and allowed the plugin updates to work as expected.