This may be unrelated, but I have had some serious issues with my Virgin domestic 350/35 service related to IP assignment over recent months.
The Virgin Hub 3 is used in modem mode with a router behind it requesting an IP by DHCP. All was well for months - it even kept the same IP when the previous owner of the property's hub/account was removed/closed and mine connected/started the next day.
At the start of October my router suddenly couldn't get an IP. The normal procedure is that the VM Hub serves a local IP in the 192.168.100.x range until the modem is registered on the cable network, then a DHCP NAK is sent from a server somewhere (not the CPE) followed by assignment of a globally routable IP.
Setting the Virgin box to router mode it wouldn't even receive an IP - on their CPE the status page the error was No Internet (Access Denied). VM swore blind there was nothing wrong with the account or their equipment and refused to raise a fault ticket as I wasn't at home to connect by wifi... head meet wall scenario. The problem resolved itself the next day with no action on my part.
About a month later a similar issue came up - this time I changed the router MAC address and was immediately served a new IP, and curiously my latency improved by 2-3ms a day later. The CMTS MAC remained the same, but something else clearly changed in VM's network.
Now if only they'd do something about the peak time congestion - the SamKnows box averages only 120Mbit at 10pm. But it will be a useful lever for getting out of contract when the OR FTTP build completes.