Spacebridge with 3rd Party USB Modem

[west2788]

Hi all,

I’ve been a Hologram fan for years and was delighted to see the Spacebridge feature. I tried it out, but so far have had no success connecting to my device.

My setup:

Remote device:

• Raspberry Pi 4B
• Raspbian Bookworm 64bit Lite
• SSH enabled, and confirmed I can SSH locally via Putty
• Quectel EC25-A Modem with PCIe to USB adapter
• Using ModemManager
• I can run ping -I wwan0 www.google.com successfully, so the modem is working and it’s also showing as Connected|LTE on the Hologram Dashboard

Local Device:

• Desktop PC with Win10 and Spacebridge client

What I’ve tried:

• Created tunnel using Spacebridge client, passing in my API key, selecting the correct SIM and entering 5000 as local port and 22 as remote port
• Opening Putty with 127.0.0.1 as IP and 5000 as port

I get:

*PuTTY Fatal Error: Remote side has unexpectedly closed the connection.

Debug info:

ip route

default via 192.168.1.1 dev wlan0 proto dhcp src 192.168.1.32 metric 600
default via 10.99.102.136 dev wwan0 proto static metric 700
10.99.102.128/28 dev wwan0 proto kernel scope link src 10.99.102.135 metric 700
192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.32 metric 600

ip a

5: wwan0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000
    link/none
    inet 10.99.102.135/28 brd 10.99.102.143 scope global noprefixroute wwan0
       valid_lft forever preferred_lft forever

ping -I wwan0 www.google.com -c 5

PING www.google.com (142.250.176.196) from 10.99.102.135 wwan0: 56(84) bytes of data.
64 bytes from lga34s37-in-f4.1e100.net (142.250.176.196): icmp_seq=1 ttl=52 time=469 ms
64 bytes from lga34s37-in-f4.1e100.net (142.250.176.196): icmp_seq=2 ttl=52 time=429 ms
64 bytes from lga34s37-in-f4.1e100.net (142.250.176.196): icmp_seq=3 ttl=52 time=388 ms
64 bytes from lga34s37-in-f4.1e100.net (142.250.176.196): icmp_seq=4 ttl=52 time=348 ms
64 bytes from lga34s37-in-f4.1e100.net (142.250.176.196): icmp_seq=5 ttl=52 time=309 ms

Is there a solution to my problem? Or does Spacebridge currently only work with the Hologram Nova?

[west2788]

I was able to resolve the issue by setting wwan0 (the modem interface) as the default route.

Get the gateway IP:

ip route show dev wwan0

Delete existing default route:

ip route del default

Add new default route:

ip route add default via <gateway_ip> dev wwan0

Now everything works as expected and I can establish a tunnel. Leaving this here in case it’s helpful for anyone else.