We are migrating the Swiss xCloud[1] and DANA[2] proxy that is reachable as {dana,tika,xcloud}.ch3.activeguard.io. Some downtime during the migration of the proxy is to be expected.
The domain name stays the same, but the IP pointed to will change. See [1] or [2] for the previous and new IP for ch3 in case you are using an IP or IP+DNS based whitelist or firewall.
There should be no availability impact as MTAs have multiple xCloud and DANA nodes configured and load balancing/failover will handle this. In some cases when there are less than the recommended 3 nodes configured some alerts relating to unavailable DANA or xCloud nodes could show up and can be ignored.
[1] https://docs.xorlab.com/latest/network-guide/#for-ch-operation-only-customers
[2] https://docs.xorlab.com/latest/network-guide/#for-ch-operation-only-customers_1