IBM cloud specifically or just in general?

I didn't use their hypervisors, but I've had a lot of experience troubleshooting their networks. They've gotten a lot better at proactive monitoring, but we used to occassionally find some private networking paths that were having trouble, and until we narrowed it down, it was hard to find. (I dunno, I guess you can't just ask all the routers if there are any ports with errors, but sure enough, when they found the right port, there was usually a huge error count, or something)

The key thing is each IP 5-tuple (peerA, peerB, protocol, portA, portB) will always take the same path over their network (most likely a different path for return packets, when A and B are switched), so in order to properly probe, you need to probe on a lot of of port combos, and once you find a broken combo, you need to run MTR on those ports, so you can give them the MTR that shows the issue.

Or, if you can, have your internode protocol run on multiple connections and drop connections that are showing issues, and let a different customer file the tickets :)

(email is in my profile if you want to discuss)