#6568 [Bug]: empty REALITY minClientVer breaks Mihomo/Clash clients despite being documented as "all versions allowed"; on Xray-core 26.9.9 they cannot connect at all

Describe the bug

Two separate problems with a VLESS + XHTTP + REALITY inbound, both affecting only Mihomo/Clash-based clients. Xray-based clients (Happ, Incy) are unaffected in every case, and a Hysteria2 inbound on the same server always works.

Empty minClientVer does not behave as documented. The documentation states that leaving Min client version empty allows all client versions. In practice, with the field empty, Mihomo/Clash clients cannot establish a REALITY connection: the node never responds and shows no latency. Setting the field to an explicit low value (1.1.1) makes them work again. Nothing else in the inbound was changed.
On Xray-core 26.9.9, Mihomo/Clash clients cannot connect at all. With Xray-core 26.9.9 the same inbound does not work for Mihomo/Clash clients regardless of the minClientVer value or any other setting I tried. The only version where they connect is 26.7.28 (with minClientVer set to 1.1.1). Xray-based clients connect fine on both cores.

In both cases the failure is silent on the server: the panel shows the inbound as running and Xray-core logs nothing about the failed connections.

How to reproduce the problem

Open the Inbounds page.
Create a VLESS inbound with network xhttp and security reality, leaving Min client version empty.
Connect with a Mihomo-based client (tested: Mihomo core v1.19.30, Clash Verge and Koala Clash). Observe that the node does not connect and shows no latency, while an Xray-based client (Happ/Incy) using the same inbound connects normally.
Set Min client version to 1.1.1, save, and reconnect the Mihomo client on Xray-core 26.7.28 — it now works.
Switch Xray-core to 26.9.9 in Xray Settings and reconnect the same Mihomo client — it stops working again, with any value of Min client version.

Expected behavior

An empty minClientVer should allow all client versions, as documented, including non-Xray clients. Mihomo/Clash clients should be able to connect to a REALITY inbound on Xray-core 26.9.9.

Actual behavior

With minClientVer empty, REALITY authentication fails for Mihomo/Clash clients on any core version. On Xray-core 26.9.9, REALITY authentication fails for Mihomo/Clash clients even with minClientVer set explicitly. No error is logged on the server in either case.

Relevant logs

Server side: panel and Xray-core logs contain nothing about the failed connection attempts.

Client side (Mihomo core v1.19.30), repeated for every attempt:

REALITY localAddr: <server-ip>:443 is using X25519MLKEM768 for TLS' communication: false
REALITY Authentication: false, AEAD: *gcm.GCM

Screenshots

No response

3x-ui version

3.8.5

Xray-core version

26.7.28 and 26.9.9

How did you install 3x-ui?

install.sh script

Operating system

Ubuntu 24.04

Which parts of the panel are affected?

Xray config generation

Browser (only if it is a UI bug)

No response

Is the panel behind a reverse proxy or CDN?

None

Before submitting

I searched existing issues and this bug has not been reported.
I am running the latest released version of 3x-ui (or have verified the bug still exists on it).
This bug report is written in English.
I have redacted any sensitive data (tokens, real domains, client UUIDs).