Admin 5.0.3 shows no reaction if another ioBroker with Admin 4 is running in the network

[Feuer-sturm]

I use proxmox with LXC containers to run my ioBroker.
I have container 108 with ioBroker productive system and container 3108 with iobroker testsystem and Admin 5.0.3

container 108 configuration (ioBroker production)
ip: 192.168.178.54
ioBroker admin: ip: 192.168.178.54:8081
js-controller: 3.2.16
admin: 4.2.1

container 3108 configuration (ioBroker test system)
ip: 192.168.178.77
ioBroker admin: ip: 192.168.178.77:8081
js-controller: 3.2.16
admin: 5.0.3

If I start ioBroker in both containers both systems are very slow / unuseable (e.g. opening Adapters or Instances) and I get the following errors in the browser

ioBroker production system container 108

ioBroker test system container 3108

[Feuer-sturm]

I think I found my problem. Both containers had the same MAC address. I changed the MAC address of the container of the testsystem and it looks like that the error is gone. Both systems can be run in parallel.