Potential causes for UDP issues when using Mosh
If you see an error that Prompt is “connected to mosh-server and waiting for UDP traffic”, that’s an indicator that something is blocking UDP communication between Prompt and the destination server.
There are a variety of reasons that UDP traffic can be blocked, but the most common culprits are typically firewall rules, port forwarding, or a third-party app such as Little Snitch or Lulu.
If you are unfamiliar with configuring these settings, consult your system or network administrator before making changes as they could could break local networking and/or have security implications.
Using Eternal Terminal as a Workaround
If you are unable to change the network settings on your Mac running Prompt, you may want to consider connecting using Eternal Terminal instead of Mosh.
Eternal Terminal works entirely over TCP. This makes ET less optimal then Mosh when connecting over low-bandwidth or high-latency connections, but it’s identical or better to mosh in all other areas.
You can connect to an Eternal Terminal server and move between networks, even going WiFi to mobile (or vice-versa), and maintain the connection. If you don’t specifically need Mosh’s excellent support for very slow networks, it might be worth trying ET instead.
Both Mosh and Eternal Terminal require specific software to be installed on the destination server. If you are unsure what connection types are supported by your server, please contact your system administrator.