upstream proxy not working for udp based connections

[siq0o]

As the title, using a socks5 upstream proxy doesn't work as intended for quic or wireguard. only h2 works.
Using aether version 1.8.0
Tested both xray-core and sing-box for mixed (http + socks5) local inbound. Same happens when using a socks5 only inbound.

[2026-08-30T12:18:42.872Z INFO  aether] [*] hunting for a working WireGuard endpoint (handshake + data-plane verification, aethernoize='balanced')
[2026-08-30T12:18:42.873Z INFO  aether::wg_prober] [*] wireguard scan mode=balanced ip=ipv4 candidates=2535 ports=[2408, 500, 1701, 4500, 854, 859, 864, 878, 880, 890, 891, 894, 903, 908, 928, 934, 939, 942, 943, 945, 946, 955, 968, 987, 988, 1002, 1010, 1014, 1018, 1070, 1074, 1180, 1387, 1843, 2371, 2506, 3138, 3476, 3581, 3854, 4177, 4198, 4233, 5279, 5956, 7103, 7152, 7156, 7281, 7559, 8319, 8742, 8854, 8886] concurrency=8 per_probe=7s budget=80s
[2026-08-30T12:18:42.873Z INFO  aether::upstream] [+] dialling out through the socks5 proxy at 127.0.0.1:2080
[2026-08-30T12:18:42.876Z INFO  aether::upstream] [+] 162.159.192.1:2408 is reached through the upstream relay at 127.0.0.1:41445
[2026-08-30T12:18:42.877Z INFO  aether::upstream] [+] 162.159.195.1:500 is reached through the upstream relay at 127.0.0.1:46212
[2026-08-30T12:18:42.877Z INFO  aether::upstream] [+] 162.159.193.1:854 is reached through the upstream relay at 127.0.0.1:43726
[2026-08-30T12:18:42.877Z INFO  aether::upstream] [+] 162.159.195.7:864 is reached through the upstream relay at 127.0.0.1:49955
[2026-08-30T12:18:42.877Z INFO  aether::upstream] [+] 188.114.97.1:4500 is reached through the upstream relay at 127.0.0.1:48974
[2026-08-30T12:18:42.877Z INFO  aether::upstream] [+] 162.159.192.109:859 is reached through the upstream relay at 127.0.0.1:37855
[2026-08-30T12:18:42.878Z INFO  aether::upstream] [+] 188.114.96.1:1701 is reached through the upstream relay at 127.0.0.1:39580
[2026-08-30T12:18:42.878Z INFO  aether::upstream] [+] 188.114.96.186:878 is reached through the upstream relay at 127.0.0.1:52108
[2026-08-30T12:18:49.880Z INFO  aether::upstream] [+] 188.114.97.114:880 is reached through the upstream relay at 127.0.0.1:42960
[2026-08-30T12:18:49.880Z INFO  aether::upstream] [+] 188.114.98.22:890 is reached through the upstream relay at 127.0.0.1:54552
[2026-08-30T12:18:49.880Z INFO  aether::upstream] [+] 188.114.99.118:891 is reached through the upstream relay at 127.0.0.1:38432
[2026-08-30T12:18:49.881Z INFO  aether::upstream] [+] 162.159.193.74:894 is reached through the upstream relay at 127.0.0.1:42032
[2026-08-30T12:18:49.881Z INFO  aether::upstream] [+] 188.114.96.13:928 is reached through the upstream relay at 127.0.0.1:59368
[2026-08-30T12:18:49.881Z INFO  aether::upstream] [+] 188.114.97.151:934 is reached through the upstream relay at 127.0.0.1:32994
[2026-08-30T12:18:49.881Z INFO  aether::upstream] [+] 162.159.195.59:908 is reached through the upstream relay at 127.0.0.1:51909
[2026-08-30T12:18:49.882Z INFO  aether::upstream] [+] 162.159.192.140:903 is reached through the upstream relay at 127.0.0.1:39098
^C

As you can see, destination address is missing:

INFO[0016] [1577682365 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42244
INFO[0016] [2324316092 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42254
INFO[0016] [1214828742 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42270
INFO[0016] [3450928520 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42278
INFO[0016] [1248894566 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42282
INFO[0016] [1518438760 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42286
INFO[0016] [2433075314 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42292
INFO[0016] [3518812435 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:42300
INFO[0023] [3439721691 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59684
INFO[0023] [3075396457 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59694
INFO[0023] [1544402063 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59706
INFO[0023] [130398748 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59722
INFO[0023] [3548207176 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59730
INFO[0023] [1675096231 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59734
INFO[0023] [3579300096 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59740
INFO[0023] [1800561169 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:59748

Here is what it would've looked like if the destination address wasn't missing:

INFO[0166] [2853345484 0ms] inbound/mixed[mixed-in]: inbound connection from 127.0.0.1:52318
INFO[0166] [2853345484 0ms] inbound/mixed[mixed-in]: inbound packet connection to 162.159.192.1:2408