Describe the bug

Sometimes the Internet fails entirely when Shadowsocks keeps running for a while. This is a new bug introduced around v5.1.7 until latest master.

To Reproduce
Steps to reproduce the behavior:

1. Start Shadowsocks
2. Wait until your Internet is dead
3. Restart service and verify that it is back working again

Expected behavior
Shadowsocks should work 24/7.

Relevant logcat

ERROR dns udp 127.0.0.1:38945 query message parse error: dns class value unknown: 2287

This message is repeated 6 times over 4 seconds, around when the DNS goes down. Not sure if it is related though.

Smartphone (please complete the following information):

• Android/Chrome OS version: Android 11
• Device: Pixel 3a XL
• Version: Reproducible from v5.2.1 (9a1c677) to 1394ab3
• Last version that did not exhibit the issue: around v5.1.7

Configuration
Put an x inside the [ ] that applies.

• IPv4 server address
• IPv6 server address
• Client IPv4 availability
• Client IPv6 availability
• Encrypt method: n/a
• Route
  • All
  • Bypass LAN
  • Bypass China
  • Bypass LAN & China
  • GFW List
  • China List
  • Custom rules
• IPv6 route
• Apps VPN mode
  • Bypass mode
• Remote DNS: 1.1.1.1