Can't SSH to remote servers

I received my RPI HAT + Quectel EG25 setup today. I used the set up scripts provide by Sixfab and have a usb0 network device up and running. I can ping, do DNS queries, and fetch web pages over http and https via the cell network, but I can’t ssh out to remote servers. I’m stumped!

I have no firewalls or other port blocks on the Raspberry PI. Here’s some outputs to illustrate (I’ve obfuscated the server IP address):
I can fetch a web page from my server via USB0:

$ curl --interface usb0 http://xx.xx.xx.xx
<!DOCTYPE html>
<title>Welcome to nginx!</title>
<h1>Welcome to nginx!</h1>

I can ssh to my server over the WLAN adapter:

$ ssh -B wlan0 xx.xx.xx.xx
Welcome to Ubuntu 22.04.1 LTS (GNU/Linux 5.15.0-1026-aws aarch64)

But I can’t ssh to the same server over USB0/Cell:

$ ssh -vvv -B usb0 xx.xx.xx.xx
OpenSSH_8.4p1 Debian-5+deb11u1, OpenSSL 1.1.1n  15 Mar 2022
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug2: resolve_canonicalize: hostname is address
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/user/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/user/.ssh/known_hosts2'
debug2: ssh_connect_direct
debug1: Connecting to xx.xx.xx.xx [xx.xx.xx.xx] port 22.
debug1: ssh_create_socket: bound to
debug1: connect to address xx.xx.xx.xx port 22: Connection timed out
ssh: connect to host xx.xx.xx.xx port 22: Connection timed out

What am I missing?