need help fixing "dial tcp i/o timeout "

[pgodfrin-nov]

After upgrading the 3.5.11 one member will not start. The consistent error is:

Aug 26 15:17:13 ip-172-19-67-216 etcd[20329]: {"level":"warn","ts":"2024-08-26T15:17:13.279912Z","caller":"etcdserver/cluster_util.go:294","msg":"failed to reach the peer URL","address":"http://172.19.60.108:2380/version","remote-member-id":"66dae8f505eec6ef","error":"Get \"http://172.19.60.108:2380/version\": dial tcp 172.19.60.108:2380: i/o timeout"}
Aug 26 15:17:13 ip-172-19-67-216 etcd[20329]: {"level":"warn","ts":"2024-08-26T15:17:13.280002Z","caller":"etcdserver/cluster_util.go:158","msg":"failed to get version","remote-member-id":"66dae8f505eec6ef","error":"Get \"http://172.19.60.108:2380/version\": dial tcp 172.19.60.108:2380: i/o timeout"}

I reverted to 3.5.2 and got the same error message and have since gone back to 3.5.11.

This is an AWS environment, both members are EC2 instances. The security groups appear to be correctly defined , permitting ingress to ports 2379 & 2380. Other members tcp dial successfully...

Q1: any suggestions on a path forward?
Q2: is there a way to get more information from the error message (log is currently DEBUG)

etcd --version
etcd Version: 3.5.11
Git SHA: 3b252db4f
Go Version: go1.20.12
Go OS/Arch: linux/amd64
uname -a
Linux ip-172-19-67-216 5.15.0-1068-aws #74~20.04.1-Ubuntu SMP Tue Aug 6 19:32:13 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

[pgodfrin-nov]

Pilot error. Bad routing code in netplan. Sorry folks...!