MR7500 (M7 Ultra Telstra) not connecting to 5G on Optus – Solution / Fix

Hi,

I faced a very similar issue, but in my case it was with an MR7500 (M7 Ultra – Telstra firmware) on the Optus network in Australia. The behaviour was almost identical — device stayed on LTE only, while the same SIM worked perfectly on 5G in a phone.

Initially, I also suspected band restriction, firmware lock, or region limitations. However, after extensive testing, the root cause turned out to be different.

Here is what I found:

- The device was confirmed to be network unlocked

- Hardware and RF components were working correctly

- Firmware did not impose any 5G restriction (confirmed by both carrier and Netgear)

Despite that, the device would only attach to LTE (e.g., Band 3), and all 5G parameters showed as N/A.

The actual issue was carrier-side provisioning.

After contacting the carrier (Optus), the front-line troubleshooting (APN, restart, manual network selection) did not fix the problem. However, once escalated, the technical team performed a backend reprovisioning / subscriber profile refresh.

This likely involved:

- Reapplying 5G entitlement flags

- Refreshing the subscriber profile (HLR/HSS)

- Re-registering the device on the network

Immediately after that, the device successfully attached to 5G NSA and started working normally.

An important observation:

After performing a factory reset on the modem, the issue reoccurred (back to LTE only). This indicates that on a fresh attach, the network may not correctly recognize or provision the device for 5G until a manual refresh is done.

Based on this experience, I would suggest the following before assuming firmware or band lock issues:

1. Contact your carrier and request a:

"5G reprovisioning / backend profile refresh"

2. Ensure your SIM is fully provisioned for 5G service

3. Confirm whether your network supports NSA vs SA, as some firmware only supports NSA mode

In your case (SKT Korea), if n78 is deployed in SA mode and your device only supports NSA, that could also be a limiting factor. However, if NSA is available, then provisioning is still a strong possibility.

Conclusion:

Not all 5G connection issues are due to firmware or band lock — in some cases, it is purely a network provisioning mismatch.

Hope this helps.