Update Windows Docker image version to v6.01

[kroese]

Update Windows Docker image version to v6.01

Contains a lot of Podman networking related changes:

• Fixed NAT port forwarding in rootless Podman, where published container ports could reach the container namespace but were not forwarded onward to the VM.
• Added explicit DNAT handling for VM ports instead of relying on the container engine’s existing forwarding rules.
• Prefer nftables under Podman and legacy iptables under Docker, with automatic fallback when the preferred backend cannot access the active ruleset.
• Added a dedicated "QEMU_DNAT" chain that preserves container-owned TCP ports and forwards all remaining protocols and ports to the VM.
• Changed unqualified port entries to TCP-only; UDP forwarding now requires an explicit "/udp" suffix.
• Added inspection of existing "PREROUTING", "POSTROUTING", "FORWARD", and mangle rules, with warnings for conflicting DNAT, REDIRECT, DROP, or REJECT rules.
• Added debug output showing the existing rules that may interfere with VM networking.
• Changed iptables backend detection to test actual NAT ruleset access through both "iptables" and "iptables-save", rather than trusting the selected binary.
• Added bidirectional TCP MSS clamping for traffic entering and leaving the VM to prevent MTU-related connection stalls.
• Broadened forwarding rules to permit traffic between the VM bridge and any external interface instead of depending on established-connection matching.
• Changed masquerading to apply to the configured VM subnet leaving through any non-bridge interface.

So #813 should be good to go.

Another notable feature is audio support in noVNC, and much more helpful error messages when the .iso download fails.

[aheck1861-debug]

Why are we still stuck on Winboat version 0.9.0 ?? You guys have been making a huge amount of changes, but none are reflected in version update numbers.

[TibixDev]

Thank you, this should help a lot of users, especially once we ship a new release! :)

[kroese]

Can you merge this one too?

[TibixDev]

Why are we still stuck on Winboat version 0.9.0 ?? You guys have been making a huge amount of changes, but none are reflected in version update numbers.

Because 0.9.0 is the most stable version we've got at the moment, 1.0 or whatever we decide to call it is not ready yet and we don't wanna ship something half assed with only a few decent-ish changes. Work has slowed down significantly the past months due to a bunch of factors that I might talk about in the 1.0 blog post, it's only now picking back up to a reasonable pace. 2026 is really not my year so far, I'm sorry, I'm trying to do better, it's just that life hasn't been the easiest lately.

[kroese]

@TibixDev I hope things get better soon!

By the way, there are a lot of good pull requests, so instead of doing the hard work yourself, maybe its an idea to merge more of them to take the load of your back.

This one is a very cool example: #776

But there are many others that fix valid issues and were never merged.