@layden87 with the 1 Gb service, you should be using the white CODA-4582 modem as that is the only modem authorized for that service unless you're running the new Ignite TV service which uses the XB6 modem. Can you confirm that you have the white CODA-4582 modem please.
If so, can you log into your modem and navigate to the BASIC ..... GATEWAY FUNCTION tab. The Router mode indication is a mode indicator (with blue background) and a mode selector. If the Router Mode indicates Dual, please change it to IPV4 by clicking or selecting IPV4 and then Save the Changes at the bottom of the tab. The modem will take a couple of minutes to switch to IPV4 mode only. I usually run a modem reboot whenever I do this, which is located in ADMIN ..... DEVICE RESET .... Reboot.
While the modem is rebooting, can you restart the problem device as well. After the reboots are completed, give Instagram a go and see if running IPV4 solves the issue.