iPhone 17 Pro Max iPhone 17 (Pro / Pro Max) – FIXED! - Cellular modem fails to recover after signal loss

[kawa636r]

Final update (looks resolved in iOS 26.3 dev beta)



Apple released iOS 26.3 for developers today and I installed it immediately to test.



Key changes observed:

• Modem firmware downgraded from 1.20.06 → 1.20.03
• Carrier bundle updated for Movistar and Orange to 67.5.1

With this combination, I have not been able to reproduce the modem lock / “No Service but reachable” issue that was consistently reproducible before (loss of signal after Wi-Fi / coverage transitions, calls ringing for caller but never reaching the device).



After ~1h+ of testing in the same locations and conditions, the modem now recovers signal correctly every time.



This strongly suggests the root cause was carrier bundle + modem firmware interaction, not hardware.



Thanks to everyone who contributed — and hopefully this helps others who were seeing similar behavior.

 

[robrobrobro]

A lot of what you posted is over my head, but I've had some strange connectivity/wifi issues on my Air. I occasionally notice RCS messages not sending or receiving, or there's a delay. Wifi also seems to have problems- the range doesn't seem as good as my 13 Pro was in my house, and sometimes wifi doesn't seem to work at all even when in range and the icon says it's connected. Could these coming updates help that?

 

[kawa636r]

Update: iOS 26.3 did not fully fix the issue.

The modem lock / missed incoming calls still occurred, just less frequently.

After further investigation, I found a reliable workaround:

• Go to Settings → Cellular → Network Selection
• Disable Automatic
• Manually select your carrier (Movistar / Orange)

Since doing this, the issue has not reappeared across:

• iPhone 17 Pro Max (mine)
• iPhone 17 Pro (my wife)
• Another iPhone 17 from a coworker
  (both physical SIM and eSIM, Movistar & Orange)

Signal behavior is dramatically better (2G fallback now works, fewer drops, no modem freeze, hotspot stable).
This strongly points to a network selection / baseband roaming logic issue in Spain, not hardware.
Worth trying if you’re affected.

 

[Tsepz]

Update: iOS 26.3 did not fully fix the issue.

The modem lock / missed incoming calls still occurred, just less frequently.

After further investigation, I found a reliable workaround:

• Go to Settings → Cellular → Network Selection
• Disable Automatic
• Manually select your carrier (Movistar / Orange)

Since doing this, the issue has not reappeared across:

• iPhone 17 Pro Max (mine)
• iPhone 17 Pro (my wife)
• Another iPhone 17 from a coworker
  (both physical SIM and eSIM, Movistar & Orange)

Signal behavior is dramatically better (2G fallback now works, fewer drops, no modem freeze, hotspot stable).
This strongly points to a network selection / baseband roaming logic issue in Spain, not hardware.
Worth trying if you’re affected.

Thanks a lot, giving this a try, I actually remember this worked well on my older Symbian and Android phones too at my old place that had week signal.

 

[kawa636r]

What about your trial? Mine worked perfect 🙂

 

[kawa636r]

Hi!

It is Gon from Valladolid, Spain. I experienced the same exact issues with Movistar myself and iPhone 17. Every single time I go to the parking lot in the basement I would lose the connection until airplane mode is toggled.

I also traveled to Swiss and experienced some outages with an Holafly eSIM. However, most of the times abroad I would only get LTE which I feel reduced the impact.

I’m also quite desperate with this bug, it is quite annoying; I just hope it is software only…

Cheers mate and thanks for reporting it so thoroughly 🙂

how it went after our last call? did you solved the issue putting the mobile phone in manual mode?

 

[Octavius8]

Update – Incoming calls not delivered while device appears attached to LTE​

Quick update with an important additional symptom I’ve now been able to document.
While the device is in the failed state (after losing signal and re-entering coverage, without toggling Airplane Mode):

• Field Test Mode shows:
  • Valid LTE cell (PCI / Cell ID present)
  • RSRP around –110 to –112 dBm
  • RSRQ around –7 dB
  • SINR degraded (–15 to –20 dB), but not zero
• The phone may still show No Service or frozen connectivity

However, when someone calls my number during this state:

• The caller hears normal ringing tones
• The network clearly treats the device as reachable
• The iPhone does not receive the call at all
  • no ringing
  • no UI notification
  • no missed call entry after recovery

In other words, the device appears to be registered on the network but fails to respond to paging until the baseband is manually reset via Airplane Mode.

This goes beyond “poor signal” and points to an attached-but-unreachable modem state, which explains why calls can be silently missed even when LTE metrics look reasonable.

Still seeing this behavior on iOS 26.2.

If anyone else is testing this, pay attention not only to data recovery, but also whether incoming calls are actually delivered after returning from a no-signal area.

I have exactly the same problems!!!
I am in 17 pro max, now in 26.4.1.