can only ping remote pod ip in gateway node from each side

[zero2hj]

What happened:
After join the two clusters, It seems I can only ping remote pod IP in submariner gateway nodes although diagnose show no errors besides kube-proxy mode issue.
What you expected to happen:

How to reproduce it (as minimally and precisely as possible):
I was connecting two clusters A,B.
For A, its cluster version is 1.19, calico version 3.15.
For B, it's 1.28 & 3.25.
Thing was built in an unconventional way, because A has been running for a long time with calico in ipip mode and kube-proxy in ipvs mode which submariner doesn't support.I have try to change the situations by migrating the mode of calico and kube-proxy.
I didn't not rebuild existing svc so you may see ipvs device in gather result.
Anything else we need to know?:

Environment:

• Diagnose information (use subctl diagnose all):

subctl diagnose all --context A
 ✓ Checking Submariner support for the Kubernetes version
 ✓ Kubernetes version "v1.19.10" is supported

 ✓ Non-Globalnet deployment detected - checking that cluster CIDRs do not overlap
 ✓ Checking DaemonSet "submariner-gateway"
 ✓ Checking DaemonSet "submariner-routeagent"
 ✓ Checking DaemonSet "submariner-metrics-proxy"
 ✓ Checking the status of all Submariner pods
 ✓ Checking that gateway metrics are accessible from non-gateway nodes

 ✓ Checking Submariner support for the CNI network plugin
 ✓ The detected CNI network plugin ("calico") is supported
 ✓ Calico CNI detected, checking if the Submariner IPPool pre-requisites are configured
 ✓ Checking gateway connections
 ✓ Checking route agent connections
 ✗ Checking Submariner support for the kube-proxy mode
 ✗ The cluster is deployed with kube-proxy ipvs mode which Submariner does not support
 ✓ Checking that firewall configuration allows intra-cluster VXLAN traffic

• Gather information (use subctl gather):
  gather-a.zip

• Cloud provider or hardware configuration:

• Install tools:
  subctl 0.19.1

• Others:

Thanks for your work.