ebay has many D-Link/US Cellular DWR-961's for sale right now...

I purchased 1 DWR-961 (US Cellular) last year and it works great with an ATT tablet SIM/account. The one I purchased last year has a firmware version from I believe 2017 (I have to stop by the location where it is installed to get the exact firmware rev/date).

I purchased 3 DWR-961's (US Cellular) recently and they will not work with an ATT or T-Mobile tablet plan SIM.

Of the 3 DWR-961's I just purchased, 2 of them have firmware V01.01.3.016 18/04/2018 and the 3rd one has firmware V01.02.3.019 03/10/2019.

I read in an ebay review/post about the DWR-961 (US Cellular) that any firmware from 2018 or 2019 SIM "locks" the device to US Cellular.

I called US Cellular to ask about one of the devices, gave them the IMEI and they said the device is definitely not SIM locked to USCC nor was it blacklisted/past due account association/etc.

Does anyone know if older firmware versions of the DWR-961 (US Cellular) are available? If is is indeed SIM locked, can it be unlocked?

I called US Cellular again to ask about firmware and they had no idea.

I chatted with D-Link and they said they do not support the DWR-961 US Cellular and to call US Cellular for support...

Any info would be great!