I have a test application with 1 seed node and two service nodes.
After migrating to .NET Core 2.1, I have some "Can't join seed-node" issues using Akka.net 1.3.6 / 1.3.8. The software is build and executed in docker with official Microsoft .NET Core 2.1 Images (microsoft/dotnet:2.1-sdk and microsoft/dotnet:2.1-runtime). Sometimes the nodes get connected without problems, sometimes I have the "can't join seed-nodes"-problems without any changes.
The problem appears on my local laptom and on our docker-server (and some other test-Systems).

The same application caused no problems running it on windows through Visual Studio.
Migration back to ".NET Core 2.0" solved the problem for now. (Project-Settings and other microsoft/dotnet:2.0-docker-Images).