Something similar to this should do the trick, provided they will let you use CPE away from a basic cable modem: Arris Touchstone TM1602A DOCSIS 3.0 Upgradeable 16x4 Telephony Modem for TWC & Optimum (Renewed) https://www.amazon.com/dp/B07CSDSBZB/ref=cm_sw_r_cp_apa_i_vpcfDb64P180X

Just buy a TM1602A yourself off of Amazon. Save $10/month off your bill in the process.

https://www.amazon.com/Touchstone-TM1602A-Upgradeable-Telephony-Optimum/dp/B07CSDSBZB/

You don't even need Optimum's help to register it. Just follow the instructions in this sub's FAQ.

Then, you will have the freedom to use whatever Router you want.