help request: apisix-1.sock failed (111: Connection refused)

### Description

I've used the java-plugin(0.4) for authentication and authorisation in Apisix, and have deployed 5 nodes, each with 2 CPU 8G RAM. It runs fine daily, however, if the number of requests per second exceeds 400, or it has been running for some time, it will then error. The error log is as follows:

2024/11/06 01:23:46 [error] 106#106: *1347056151 [lua] init.lua:889: phase_func(): failed to connect to the unix socket unix:/usr/local/apisix/conf/apisix-1.sock: connection refused, client: 192.60.6.1, server: _, request: "POST /XXXX HTTP/1.1", host: "xxxx.com:80"
2024-11-06 09:23:46.327
2024/11/06 01:23:46 [warn] 106#106: *1347056151 [lua] plugin.lua:1107: run_plugin(): ext-plugin-pre-req exits with http status code 503, client: 192.60.6.1, server: _, request: "POST /XXXX HTTP/1.1", host: "xxx.com:80"
2024-11-06 09:23:46.327
2024/11/06 01:23:46 [error] 106#106: *1347056151 connect() to unix:/usr/local/apisix/conf/apisix-1.sock failed (111: Connection refused), client: 192.60.6.1, server: _, request: "POST /xxxx HTTP/1.1", host: "xxx.com:80"

Could this issue be occurring due to some configuration problem or is it something else? What can I do to prevent it?

### Environment

- APISIX version (run `apisix version`): 3.6.0
- Operating system (run `uname -a`):
- OpenResty / Nginx version (run `openresty -V` or `nginx -V`):
- etcd version, if relevant (run `curl http://127.0.0.1:9090/v1/server_info`):
- APISIX Dashboard version, if relevant: 3.0
- Plugin runner version, for issues related to plugin runners: ext-plugin-pre-req, ext-plugin-post-resp
- LuaRocks version, for installation issues (run `luarocks --version`):