Hi,
I’m seeing a persistent cellular connectivity issue with a Raspberry Pi using
a Sixfab 4G LTE HAT and a Telit LE910C4-NF.
Current behavior:
- LTE registration succeeds
- the modem attaches successfully
- the cellular interface gets an IP address
- ICMP ping works over the cellular interface
- UDP DNS works at least to 8.8.8.8:53
- but TCP/HTTP/HTTPS over cellular times out
What we already tested:
- account is active and not over limit in Sixfab Connect
- modem-side data session works
- modem-side ping works
- switched from ECM mode to QMI mode
- re-enabled ModemManager / NetworkManager
- QMI bearer comes up successfully and gets an IP
- tested multiple public endpoints over the cellular interface
- forced registration attempts on both T-Mobile (310260) and AT&T (310410)
Packet capture result:
- outbound TCP SYN packets leave on the cellular interface
- no SYN-ACK packets return
So at this point it does not look like an application bug on the Pi, and it no
longer looks like only an ECM-mode problem.
Has anyone seen this with a Sixfab SIM / Telit LE910C4-NF before?
Did you resolve it with a SIM/network session reset, carrier/profile change,
or something else on the Sixfab side?
I’m also opening a direct support case with Sixfab, but I wanted to ask here
in case anyone has seen the same pattern.
Thanks