Tunnel on cellular modem: high data usage + shuts down

teamacct · January 24, 2023, 9:33pm

We are using tunnels successfully at 3 customer sites via cellular modems/Twilio SIMs. Is IoT with some user interaction. We assign each to 2 subdomains, for HTTP and VNC Application access.
Are there settings to help with these? We haven’t found any. 2 issues:
1-- Just running a tunnel (very little real data) uses nearly 4MB/hour, which becomes expensive. Any way to reduce that by 50-70%? OK to have only 1-2 connections vs the standard 4. Also OK to have much less what we assume to be “heatbeat” traffic. (We had tried ngrok which did not create this usage but worked fine.)
2-- Power outages at 1 site occasionally take the cell modem down for 2-60 minutes. The tunnel process then just dies - don’t have details yet on when or log output (site is inaccessible!). It should just patiently wait & reconnect when possible.
Thanks for any assistance.

mbk1 · February 7, 2023, 7:18pm

Having the same issue - just using the tunnel as a back door to a raspberry, so usually no real usage - but the tunnel takes around 100 MB / day…

teamacct · April 22, 2023, 10:41pm

We submitted a GitHub issue on this. This response reduces number of connections from default 4 to just 1, which indeed reduces bandwidth by 75%:
–ha-connections 1
We have submitted another issue to further reduce bandwidth of that one connection:

github.com/cloudflare/cloudflared

💡Reduce constant minimum Tunnel connection bandwidth (follow-on issue)

opened 10:27PM - 22 Apr 23 UTC

iicdev

Type: Feature Request Priority: Normal

**Describe the feature you'd like** This is specific followup request from issu…e which was closed: "Significantly reduce basic Tunnel bandwidth for cell modem #935" That response partially resolved the core issue (see below). We use cell modems at some customer sites to our AI-based BMS (building management system), running Windows, controlling tens of IoT control devices. We need to minimize expensive cell modem bandwidth. We still need each CONNECTION to consume less bandwidth. See attached screenshots, which prove each connection uses 0.8-1.1MB/hour simply to maintain itself, not counting application data exchanged. We accept lower reliability and slow reconnection of a lost connection. We would expect the solution to be sending metrics & keep-alive packets much less frequently. **Describe alternatives you've considered** --metrics-update-freq 30 (default is 5) -- in early testing, we didn't see any improvement --ha-connections 1 -- per above-referenced issue #935, that DID reduce number of connections from 4 to 1, which did indeed reduce bandwidth 75%. Thank you! **Additional context** Screenshot of cell modem traffic in MB attached. Hour periods with under 0.25MB are no Tunnel running. Those near/above 1MB are with Tunnel running, with only ONE connection (--ha-connections 1). That one connection typically consumes 1.1MB (Tunnel running)-0.25MB(Tunnel not running)=0.85MB/hour. Ignore larger MB hours - that is application or Windows traffic. ![CellModemTraffic-TunnelRunning-NotRunning](https://user-images.githubusercontent.com/121069508/233808957-26439691-a34d-4d7b-8fd1-d0864ba7ad11.jpg)