@gurman23 seems to me that we've seen this before. If I remember this correctly it might be an IPV6 issue.
Can you log into your modem and navigate to the BASIC ..... GATEWAY FUNCTION tab. If the Router Mode indicates Dual, please change it to IPV4 and Save the Changes. The modem will take a couple of minutes to switch to IPV4 mode only. I usually run a modem reboot whenever I do this, 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. If so, you need a network engineer to determine what the problem is with your Cable Modem Termination System (CMTS) which the modem connects to for data and control services. First things first, can you check on the Router Mode that the modem is operating in and switch it to IPV4 mode for test purposes.
Can you have a look at the following post, which is also in this thread: