[cluster setup]The first setup 3 agency is failed.

[yangchao0512]

My Environment

ArangoDB Version: 3.6.3
Storage Engine: RocksDB
Deployment Mode: Cluster
Deployment Strategy: Manual Start
Configuration: cluster setup details
Infrastructure: own
Operating System: centos7
Total RAM in your machine: 64GiB for 6 machines
Disks in use: HDD
Used Package: RedHat .rpm

Component, Query & Data

Affected feature:

The cluster can‘t use anymore

AQL query (if applicable):

AQL explain (if applicable):

Dataset:

Size of your Dataset on disk:
50GB

Replication Factor & Number of Shards (Cluster only):

Replication Factor 3
Number of Shards 3

Steps to reproduce

agency node：
56.18.30.240
56.18.30.241
56.18.30.242
dbserver node and coordinator node：
56.18.30.243
56.18.30.244
56.18.30.245

1. 56.18.30.240
   arangod --server.endpoint tcp://0.0.0.0:8531
   --agency.my-address tcp://56.18.30.240:8531
   --server.authentication false
   --agency.activate true
   --agency.size 3
   --agency.endpoint tcp://56.18.30.241:8531
   --agency.endpoint tcp://56.18.30.242:8531
   --agency.supervision true
   --database.directory /var/lib/arangodb3/agency8531/data

2. 56.18.30.241
   arangod --server.endpoint tcp://0.0.0.0:8531
   --agency.my-address tcp://56.18.30.241:8531
   --server.authentication false
   --agency.activate true
   --agency.size 3
   --agency.endpoint tcp://56.18.30.240:8531
   --agency.endpoint tcp://56.18.30.242:8531
   --agency.supervision true
   --database.directory /var/lib/arangodb3/agency8531/data

3. 56.18.30.242
   arangod --server.endpoint tcp://0.0.0.0:8531
   --agency.my-address tcp://56.18.30.242:8531
   --server.authentication false
   --agency.activate true
   --agency.size 3
   --agency.endpoint tcp://56.18.30.240:8531
   --agency.endpoint tcp://56.18.30.241:8531 \
   --agency.supervision true
   --database.directory /var/lib/arangodb3/agency8531/data

Problem:
The third node（242） error message：
[root@localhost arangodb3]# arangod --server.endpoint tcp://0.0.0.0:8531 \

--agency.my-address tcp://56.18.30.242:8531
--server.authentication false
--agency.activate true
--agency.size 3
--agency.endpoint tcp://56.18.30.240:8531
--agency.endpoint tcp://56.18.30.241:8531
--agency.supervision true
--database.directory /var/lib/arangodb3/agency8531/data
2020-08-26T01:22:35Z [25679] INFO [e52b0] ArangoDB 3.6.3-1 [linux] 64bit, using jemalloc, build tags/v3.6.3.1-0-g76b2e00b64b-dirty, VPack 0.1.33, RocksDB 6.2.0, ICU 58.1, V8 7.1.302.28, OpenSSL 1.1.1g 21 Apr 2020
2020-08-26T01:22:35Z [25679] INFO [75ddc] detected operating system: Linux version 3.10.0-123.el7.x86_64 (builder@kbuilder.dev.centos.org) (gcc version 4.8.2 20140120 (Red Hat 4.8.2-16) (GCC) ) #1 SMP Mon Jun 30 12:09:22 UTC 2014
2020-08-26T01:22:35Z [25679] INFO [25362] {memory} Available physical memory: 67333894144
2020-08-26T01:22:35Z [25679] WARNING [3e451] {memory} It is recommended to set NUMA to interleaved.
2020-08-26T01:22:35Z [25679] WARNING [b25a4] {memory} put 'numactl --interleave=all' in front of your command
2020-08-26T01:22:35Z [25679] INFO [43396] {authentication} Jwt secret not specified, generating...
2020-08-26T01:22:35Z [25679] INFO [144fe] using storage engine 'rocksdb'
2020-08-26T01:22:35Z [25679] INFO [3bb7d] {cluster} Starting up with role AGENT
2020-08-26T01:22:35Z [25679] INFO [6ea38] using endpoint 'http+tcp://0.0.0.0:8531' for non-encrypted requests
2020-08-26T01:22:35Z [25679] INFO [a1c60] {syscall} file-descriptors (nofiles) hard limit is 8192, soft limit is 8192
2020-08-26T01:22:35Z [25679] INFO [3844e] {authentication} Authentication is turned off, authentication for unix sockets is turned on
2020-08-26T01:22:35Z [25679] INFO [cf3f4] ArangoDB (version 3.6.3-1 [linux]) is ready for business. Have fun!
2020-08-26T01:22:35Z [25679] INFO [7b6f3] {agency} Entering gossip phase ...
2020-08-26T01:22:35Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:36Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:36Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:37Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:39Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:43Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:47Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:51Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:55Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:22:59Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:03Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:07Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:11Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:15Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:19Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:23Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:27Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint
2020-08-26T01:23:31Z [25679] ERROR [bed89] {agency} Got error 500 from gossip endpoint

Expected result:
how to fix