@llc0930 you have some kind of proxy intercepting the connection between webhelper and steam. Maybe a forced proxy or some other kind of filter.

From the point of view of steam the connection is coming from 192.168.69.200 according to your logs:

[2025-03-15 04:46:36] WebUITransport: Connection from: 192.168.69.200:51062
[2025-03-15 04:46:36] WebUITransport: Connection failed

And steam will reject any connection that doesn't originate from localhost.

I don't know why, I never modified the nftables config from beginning to end, but after I closed steam, I couldn't restart it immediately. I haven't updated any system packages at that time.

But before this problem occurred, due to a problem with steamwebhelper, every time I turned on the computer and executed steam for the first time, I had to restart it before it could start successfully.

Ok, I think I found what was causing the problem.
I didn't restrict the output interface that the masquerade would act on before...
Thank you for helping me clarify the problem.

table inet nat {
	chain prerouting {
		type nat hook prerouting priority dstnat; policy accept;
		# port forwarding
	}

	chain postrouting {
		type nat hook postrouting priority srcnat; policy accept;
		oifname "ppp0" masquerade persistent
	}
}