​​​​​​the firmware is part of the provisioning. So it should be pushed automatically. 

Got a screensnip of the cable connections page and event logs? That helps check the line. 

for accessing it, check this post. 
Workaround: Accessing the Cable Modem Status Page | Community (surfboard.com)

i am having the same exact issue. i login to the interface using “192.168.0.1” not the one you gave. so i saw in the logs there was a failed update. i am stuck on docsis3.0 and to even get to this page to type my responce felt like i was on Dial up internet. i am told i should just get a new modem. so i will have to deal with it until i get paid again or it fixes itself before then. it does keep tryting to go to docsis3.1 the blue light comes on only for a few seconds then goes back.

We don't check the Event Logs as it been monitored by you’re ISP , so please share the screenshot of the cable signal levels of sb8200:

Please check the below link for the same :