Thank you for your query.
In terms this your mentioned warning. Currently, as you probably know, the only available option is the SMS warning. There is a possibility to receive the SMS warning prior the mobile data limit is reached. For example, it is possible to set 1000 MB data limit and then set 800 MB on SMS warning. This would allow you to be notified in advance.
In order to implement this, please navigate to: Network -> Interfaces -> Mob1s1a1/Mob1s2a1 -> edit(pencil sign)
More information here: https://wiki.teltonika-networks.com/view/RUT950_Interfaces#Mobile_Data_Limit
However, I do apologize, I wasn't able to fully grasp "there used to be a threshold option (missing now)?". Could you please elaborate a little bit regarding this part, what exactly you meant by threshold and what kind of notification this would be?
Regarding SNMP, with the newest RUTOS firmware version SNMP package has been moved to package manager. Therefore, it needs to be installed in order to use it.
You can find more information here: https://wiki.teltonika-networks.com/view/RUT950_SNMP
Regarding the feature suggestion, thank you, I definitely can see where this could be used. However, there is an issue: to limit the bandwidth on mob1s1a1 QoS(Quality of Service) would need to be used. Unfortunately, due to the current implementation logic with our RUTOS firmware version QoS doesn't have an option to select the mobile interface mob1s1a1.
More information on QoS can be found here: https://wiki.teltonika-networks.com/view/RUT950_Traffic_Shaping#Interfaces
To sum up, thank you for your suggestion, however, at this point in time due to QoS limitations this wouldn't be possible to implement. QoS needs improvements in general, only then we could think of any additional development. I believe there should be an improvement in QoS with our 7.3 FW release, but unfortunately, that is not officially confirmed yet. Nevertheless, I have passed on your suggestion our R&D(Research & Development) team to have in mind when/if QoS functionality will be redone.