Specific DNS for some clients seems to be not working

### Prerequisites

- [X] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a) and found no answer

- [X] I have searched other issues and found no duplicates

- [X] I want to report a bug and not [ask a question or ask for help](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a)

- [X] I have set up AdGuard Home correctly and [configured clients to use it](https://github.com/AdguardTeam/AdGuardHome/wiki/Clients). (Use the [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a) for help with installing and configuring clients.)

### Platform (OS and CPU architecture)

Custom (please mention in the description)

### Installation

Other (please mention in the description)

### Setup

On a router, DHCP is handled by AdGuard Home

### AdGuard Home version

0.107.46

### Action

I have [setup AGH](https://openwrt.org/docs/guide-user/services/dns/adguard-home) on my OpenWrt router(23.05.5 r24106-10cc5fcd00) and have defined upstream DNS servers to
```
94.140.14.14
94.140.15.15
[/lan/]127.0.0.1:54
[//]127.0.0.1:54
```
And private reverse DNS servers to `192.168.1.1:54`.
I am using Wireguard VPN interface(wg0) on y OpenWrt along with Policy-Based-routing(PBR) to route some clients through wg0 interface.

I am trying to set custom DNS servers as per my VPN config into AGH using "Client settings" option like shown in screenshots, so that wg0 clients uses VPN DNS servers so they dont leak. However, it doesnt seem to be working properly OR I may have misconfigured something somewhere.
I tried to follow guides from wiki and other source but no luck.

Sorry for the naive question and thanks for reading my question/issue.

### Expected result

VPN clients are using DNS servers provided as default for all clients even though I have define custom DNSes in client settings.

### Actual result

ipleak shows VPN clients not using correct DNS.

### Additional information and/or screenshots

_No response_