Pods unable to resolve hostnames in Kubernetes cluster

Question

I'm working on aws eks, and I'm having issues with networking because none of the pods can resolve hostnames.

Checking the kube-config pods, I found this:

NAME                                     READY   STATUS             RESTARTS   AGE
alb-ingress-controller-68b7d9dd9-4mpnc   1/1     Running            0          3d20h
alb-ingress-controller-68b7d9dd9-kqmsl   1/1     Running            8          17d
alb-ingress-controller-68b7d9dd9-q4m87   1/1     Running            11         26d
aws-node-m6ncq                           1/1     Running            34         31d
aws-node-r8bs5                           1/1     Running            31         28d
aws-node-vfvjn                           1/1     Running            34         31d
coredns-f47955f89-4bfb5                  1/1     Running            11         26d
coredns-f47955f89-7mqp7                  1/1     Running            8          17d
kube-flannel-ds-chv64                    0/1     CrashLoopBackOff   1814       28d
kube-flannel-ds-fct45                    0/1     CrashLoopBackOff   1831       31d
kube-flannel-ds-zs8z4                    0/1     CrashLoopBackOff   1814       28d
kube-proxy-6lcst                         1/1     Running            18         31d
kube-proxy-9qfkg                         1/1     Running            17         28d
kube-proxy-l5qvd                         1/1     Running            18         31d

and kube-flannel logs are this:

I0208 21:01:23.542634       1 main.go:218] CLI flags config: {etcdEndpoints:http://127.0.0.1:4001,http://127.0.0.1:2379 etcdPrefix:/coreos.com/network etcdKeyfile: etcdCertfile: etcdCAFile: etcdUsername: etcdPassword: help:false version:false autoDetectIPv4:false autoDetectIPv6:false kubeSubnetMgr:true kubeApiUrl: kubeAnnotationPrefix:flannel.alpha.coreos.com kubeConfigFile: iface:[] ifaceRegex:[] ipMasq:true subnetFile:/run/flannel/subnet.env subnetDir: publicIP: publicIPv6: subnetLeaseRenewMargin:60 healthzIP:0.0.0.0 healthzPort:0 charonExecutablePath: charonViciUri: iptablesResyncSeconds:5 iptablesForwardRules:true netConfPath:/etc/kube-flannel/net-conf.json setNodeNetworkUnavailable:true}
W0208 21:01:23.542713       1 client_config.go:608] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
I0208 21:01:23.647398       1 kube.go:120] Waiting 10m0s for node controller to sync
I0208 21:01:23.647635       1 kube.go:378] Starting kube subnet manager
I0208 21:01:24.647775       1 kube.go:127] Node controller sync successful
I0208 21:01:24.647801       1 main.go:238] Created subnet manager: Kubernetes Subnet Manager - ip-10-23-21-240.us-east-2.compute.internal
I0208 21:01:24.647811       1 main.go:241] Installing signal handlers
I0208 21:01:24.647887       1 main.go:460] Found network config - Backend type: vxlan
I0208 21:01:24.647916       1 main.go:652] Determining IP address of default interface
I0208 21:01:24.648449       1 main.go:699] Using interface with name eth0 and address 10.23.21.240
I0208 21:01:24.648476       1 main.go:721] Defaulting external address to interface address (10.23.21.240)
I0208 21:01:24.648482       1 main.go:734] Defaulting external v6 address to interface address (<nil>)
I0208 21:01:24.648543       1 vxlan.go:137] VXLAN config: VNI=1 Port=0 GBP=false Learning=false DirectRouting=false
E0208 21:01:24.648871       1 main.go:326] Error registering network: failed to acquire lease: node "ip-10-23-21-240.us-east-2.compute.internal" pod cidr not assigned
W0208 21:01:24.649006       1 reflector.go:424] github.com/flannel-io/flannel/subnet/kube/kube.go:379: watch of *v1.Node ended with: an error on the server ("unable to decode an event from the watch stream: context canceled") has prevented the request from succeeding
I0208 21:01:24.649060       1 main.go:440] Stopping shutdownHandler...

Any idea what could be the issue or what to try?

Thanks!