[error] dnsproxy: exchange failed; unexpected EOF

### 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

Custom package (OpenWrt, HomeAssistant, etc; please mention in the description)

### Setup

On a router, DHCP is handled by the router

### AdGuard Home version

0.107.73

### Action

Looking at my OpenWrt System Log, I notice AdGuard Home outputting several [error] dnsproxy: exchange failed; unexpected EOF logs. Below is a sample of what is in the log from the last 30 minutes.

```
[26 Mar 2026 at 7:39:00 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:39:00.226160 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";google.com.\tIN\t A" duration=13.820177ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABBmdvb2dsZQNjb20AAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:39:50 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:39:50.240340 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";reddit.com.\tIN\t A" duration=6.299564ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABBnJlZGRpdANjb20AAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:44:29 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:44:29.715985 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";ctest.p01.ctest.srv.nintendo.net.\tIN\t A" duration=6.261456ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABBWN0ZXN0A3AwMQVjdGVzdANzcnYIbmludGVuZG8DbmV0AAABAAEAACkIAAAAgAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:44:29 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:44:29.716400 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";ctest.p01.ctest.srv.nintendo.net.\tIN\t AAAA" duration=8.56489ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABBWN0ZXN0A3AwMQVjdGVzdANzcnYIbmludGVuZG8DbmV0AAAcAAEAACkIAAAAgAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:45:00 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:45:00.087282 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";ctest-ipv6.p01.ctest.srv.nintendo.net.\tIN\t AAAA" duration=6.919209ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABCmN0ZXN0LWlwdjYDcDAxBWN0ZXN0A3NydghuaW50ZW5kbwNuZXQAABwAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:45:00 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:45:00.088337 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";ctest.p01.ctest.srv.nintendo.net.\tIN\t A" duration=7.359188ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABBWN0ZXN0A3AwMQVjdGVzdANzcnYIbmludGVuZG8DbmV0AAABAAEAACkIAAAAgAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:45:00 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:45:00.089912 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";ctest-ipv6.p01.ctest.srv.nintendo.net.\tIN\t A" duration=8.043561ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABCmN0ZXN0LWlwdjYDcDAxBWN0ZXN0A3NydghuaW50ZW5kbwNuZXQAAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:47:58 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:47:58.503830 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";val.p01.lp1.penne.srv.nintendo.net.\tIN\t A" duration=11.905837ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABA3ZhbANwMDEDbHAxBXBlbm5lA3NydghuaW50ZW5kbwNuZXQAAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:48:23 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:48:23.972605 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";gateway.fe2.apple-dns.net.\tIN\t AAAA" duration=3.259129ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABB2dhdGV3YXkDZmUyCWFwcGxlLWRucwNuZXQAABwAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:48:23 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:48:23.975513 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";gateway.fe2.apple-dns.net.\tIN\t A" duration=10.101727ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABB2dhdGV3YXkDZmUyCWFwcGxlLWRucwNuZXQAAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:48:56 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:48:56.904453 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";e0d67c509fb203858ebcb2fe3f88c2aa.baas.nintendo.com.\tIN\t A" duration=7.569451ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABIGUwZDY3YzUwOWZiMjAzODU4ZWJjYjJmZTNmODhjMmFhBGJhYXMIbmludGVuZG8DY29tAAABAAEAACkIAAAAgAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:48:56 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:48:56.905551 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";e0d67c509fb203858ebcb2fe3f88c2aa.baas.nintendo.com.\tIN\t AAAA" duration=8.686425ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABIGUwZDY3YzUwOWZiMjAzODU4ZWJjYjJmZTNmODhjMmFhBGJhYXMIbmludGVuZG8DY29tAAAcAAEAACkIAAAAgAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:50:40 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:50:40.261197 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";facebook.com.\tIN\t A" duration=7.425699ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABCGZhY2Vib29rA2NvbQAAAQABAAApCAAAAIAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:53:34 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:53:34.948362 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";dns9.quad9.net.\tIN\t A" duration=19.545059ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABBGRuczkFcXVhZDkDbmV0AAABAAEAACkIAAAAgAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:57:26 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:57:26.534558 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";gateway.fe2.apple-dns.net.\tIN\t AAAA" duration=6.71451ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABB2dhdGV3YXkDZmUyCWFwcGxlLWRucwNuZXQAABwAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 7:57:26 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 08:57:26.535359 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";gateway.fe2.apple-dns.net.\tIN\t A" duration=7.239269ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABB2dhdGV3YXkDZmUyCWFwcGxlLWRucwNuZXQAAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 8:04:21 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 09:04:21.652565 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";crlite-attach.adtidy.org.\tIN\t AAAA" duration=7.003334ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABDWNybGl0ZS1hdHRhY2gGYWR0aWR5A29yZwAAHAABAAApCAAAAIAAAAA\": unexpected EOF"
[26 Mar 2026 at 8:06:08 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 09:06:08.529247 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";api-global.netflix.com.\tIN\t A" duration=7.901623ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABCmFwaS1nbG9iYWwHbmV0ZmxpeANjb20AAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 8:06:35 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 09:06:35.611644 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";api-global.netflix.com.\tIN\t AAAA" duration=6.404362ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABCmFwaS1nbG9iYWwHbmV0ZmxpeANjb20AABwAAQAAKQgAAACAAAAA\": unexpected EOF"
[26 Mar 2026 at 8:06:35 pm AEDT] user.notice: AdGuardHome[1]: 2026/03/26 09:06:35.612545 [error] dnsproxy: exchange failed upstream=https://dns.quad9.net:443/dns-query question=";api-global.netflix.com.\tIN\t A" duration=7.118072ms err="requesting https://dns.quad9.net:443/dns-query: Get \"https://dns.quad9.net:443/dns-query?dns=AAABIAABAAAAAAABCmFwaS1nbG9iYWwHbmV0ZmxpeANjb20AAAEAAQAAKQgAAACAAAAA\": unexpected EOF"
```

### Expected result

No errors in system log for dnsproxy exchange failed due to unexpected EOF.

### Actual result

Errors appearing in system log for dnsproxy due to unexpected EOF.

### Additional information and/or screenshots

OpenWrt 25.12.1 (r32768-b21cfa8f8c), running on a ER605 v2, which is a MediaTek MT7621AT CPU, ramips/mt7621