So I’m not sure if this is the problem affecting your friend, however, RCS messaging uses additional ports rather than just the standard tcp/443 port to send traffic. This port is specifically tcp/5223. If your friend connects to a wireless network that has a firewall that doesn’t have the port open, then the RCS messages will fail to send/receive until they are either connected to their cellular network or a wireless network that doesn’t have that port blocked.

The catch is, if you try to send a message while you are on a network where the traffic isn’t allowed, the RCS message doesn’t attempt to resend right away after changing to a network where the traffic is allowed.

I have a firewall in my house that has very strict rules and I had to enable a firewall policy to allow this traffic to be able to send / receive RCS messages when I was connected to my home’s WiFi. My wife’s company WIFi network has that port blocked so she doesn’t connect to it anymore and RCS works just fine.

If you want to see if this is the case for your friend’s phone, have them use their mobile network while sending / receiving RCS messages to test.

3-Node ESXi cluster with 10 Debian VMs, 3 Windows VMs, and one FreeBSD VM

Examples: ServiceNow, Connectwise, Jira Service Desk

Look into getting a CMDB and keep track of all of your hardware. That can store the hostname / IPs of your KVM / OS or virtualization layer, vkernels, storage adapter IPs, your vCenters and so on and so forth. If your data is getting so big that spreadsheets are getting tough to manage, then you probable need a more enterprise method of storing it.