Here’s a simple work around…..If you have a 2nd Ethernet port or add a net adaptor to your PC assign 192.168.100.10 to it. Then get a small 5 port 2.5 gig switch and connect a cable from from the modem port to the switch and another from the switch to your router. Then connect another cable from the 2nd port on you PC at 192.168.100.10 to the new switch.
Then you’ll be able to address the CODA56 with no problem.