According to the data sheets for the gateways, both 3939 and 3941B models are capable of being monitored via SNMP: http://www.compsource.com/pdfs/pdf_new/29606.pdf
Comcast says this regarding SNMP: https://www.xfinity.com/support/internet/simple-network-management-protocol/
It is not clear whether this relates to the configuration of the gateway to allow pass SNMP traffic or actually enabling modem for monitoring. It would be nice to get read only access to the modem.
The use of SNMP on Comcast Business Gateways is an option that is available to you. Due to security concerns we adjust the configuration to have port 161 disabled by default. Pending our customers do require access to this feature, we upon request we can have our security assurance team open this port. If you would like to have this port opened please send respond to this post or private message me to assist. Thank you
Wow, brilliant! Thank you. I would love to get that set up.
Can one limit the port to be opened on just LAN side? Will SNMPv3 config be available in the web interface?
Thank you Pawel,
I have sent your request to enable the port 161 for SNMP on your gateway. Please allow a few days for your request to be processed. Though I asked for confirmation from that team as to when the port would be opened I cannot guarantee that will get back to me in a timely manner. Once I do hear from them I will message you but in the mean time feel free to test the service to ensure it is active. Additionally I was not able to confirm if the web interface would support SNMPv3. I am engaging with a few support teams to get this confirmation. Again once I receive contact from them I will update you here. I hope this helps