Ethernet/IPv4 problems

My PC is connected via Ethernet to a Comcast/Xfinity modem-router combo. Windows shows I’m “connected,” and I can browse websites like Google or YouTube (since they support IPv6), but a lot of apps won’t work at all – Discord stays stuck on “Checking for updates,” and Valorant gives me a “No Internet Found” error.

Here’s what I’ve noticed:

• ipconfig shows I’m getting valid IPv6 addresses and a gateway.

• IPv4 doesn’t work properly – when I try ping 8.8.8.8, it’s 100% packet loss.

• I tried setting manual IPv4/DNS (e.g., 172.27.35.50 / 255.255.255.0 / gateway 172.27.35.1 with DNS 8.8.8.8) but it still won’t pass traffic.

• DNS lookups to Google DNS time out, but IPv6 pings (like ping ipv6.google.com) work perfectly.

• Browser access works because it’s falling back to IPv6, but most apps and games break since they require IPv4.

What I’ve tried so far:

• Flushed DNS / reset Winsock / reset TCP-IP stack.

• Power-cycled modem and PC multiple times.

• Disabled and re-enabled the network adapter.

• Even set manual IPv4 and DNS – still no luck.

It looks like my gateway is only giving me IPv6 connectivity and not routing IPv4 to the internet. Has anyone else had their Xfinity modem-router combo do this? Is it an ISP provisioning issue or something I can fix in the settings?

Any advice would be appreciated — should I factory reset the gateway, or is this something I’ll need to call Comcast for and ask them to re-provision my modem with IPv4 enabled?