Problems with acks of ConfirmedDataup

Hello Brocaar,
You mention here:

Problems about elastic IP for Downlinks. We have a vmware server with fixed IP.
If the Gateway is 4G connected downlinks are ok. At less with our operator. If we change to Ethernet we started to lose downlinks. First only one downlink every 4 Uplinks and after 30 minutes no downlink.
Initially, we suspect routers and port forwarding but it looks ok.
Can I have problems if the gateway uses IPV6 frames instead Ipv4 or something related?

Solved. Finally loopback network problems. Two different places for Gateway and Server but VPN interconnected. After a while downlink fails. Outside the VPN level or outside this network all is ok the same as with 4G.