Researching, I believe I noticed 44.137.1.80/28 appear, and that you're the coordinator.
Otherwise, there's already a route existing in the portal.
I know, I will try to contact him to see if he has problems. (I guess he has only made a tunnel to amprgw. I cannot ping him from a Dutch AMPRnet IP)
Some people apply for a subnet on IPIP and then find that it is not as easy as they would have guessed to get it working correctly. Probably they expected it would be a matter of configuring an IP tunnel in their router. We know there is a little more to it.
Rob