Connection refused: localtunnel.me:<portnumber> (check your firewall settings)

Issue

Hello. I'm running a TCP service on port 52001. When I use localtunnel, everything momentarily works just fine---but after a few minutes of running, I always get this same error:

/usr/local/lib/node_modules/localtunnel/bin/lt.js:81
    throw err;
    ^

Error: connection refused: localtunnel.me:14889 (check your firewall 
settings)
    at Socket.<anonymous> (/usr/local/lib/node_modules/localtunnel/li
b/TunnelCluster.js:52:11)
    at Socket.emit (node:events:518:28)
    at emitErrorNT (node:internal/streams/destroy:169:8)
    at emitErrorCloseNT (node:internal/streams/destroy:128:3)
    at process.processTicksAndRejections (node:internal/process/task_
queues:82:21)

Node.js v20.18.1

Environment Info

Running Kubuntu Linux 25.04, my shell is fish

Let me know if you need any more info. I'm having another issue, which I have created along with this one.