Outbound SML lookup fails

[AlphonseSantoro]

I am in the process of upgrading our oxalis server. The inbound module works as intended and I can send files to it directly by using the option setTransmissionBuilderOverride and overrideAs4Endpoint in the request builder. Another AP has been able to send files to it successfully as well.
If I try to send a file using the outbound module as intended, without overriding endpoint, I am met with the error:

Error when looking up identifier '0192:123456789' in SML due to network error. Retry after sometime... DNS-Lookup-Err: network error
(0192:123456789 is a fake one for the sake of this issue, but it is a valid recipient that is in use in production today.)

Stacktrace

2025-07-09 16:17:46,093 DEBUG [org.xbill.DNS.config.JndiContextResolverConfigProvider$InnerJndiContextResolverConfigProvider] JNDI class: javax.naming.directory.DirContext 2025-07-09 16:17:46,094 DEBUG [org.xbill.DNS.config.ResolvConfResolverConfigProvider] Added home. to search paths 2025-07-09 16:17:46,094 DEBUG [org.xbill.DNS.config.ResolvConfResolverConfigProvider] Added /[2a02:228:0:0:0:0:53:181]:53 to nameservers 2025-07-09 16:17:46,094 DEBUG [org.xbill.DNS.config.ResolvConfResolverConfigProvider] Added /[2a02:228:0:0:0:0:53:182]:53 to nameservers 2025-07-09 16:17:46,094 DEBUG [org.xbill.DNS.config.ResolvConfResolverConfigProvider] Added /80.232.93.176:53 to nameservers 2025-07-09 16:17:46,094 DEBUG [org.xbill.DNS.config.ResolvConfResolverConfigProvider] Added /80.232.93.177:53 to nameservers 2025-07-09 16:17:46,196 DEBUG [org.xbill.DNS.Lookup] Lookup for B-7828b307e21458b6522a0ff968025a68.iso6523-actorid-upis.edelivery.tech.ec.europa.eu./A, cache answer: UNKNOWN 2025-07-09 16:17:46,198 DEBUG [org.xbill.DNS.ExtendedResolver] Sending B-7828b307e21458b6522a0ff968025a68.iso6523-actorid-upis.edelivery.tech.ec.europa.eu./A, id=49908 to resolver 0 (SimpleResolver [/[2a02:228:0:0:0:0:53:181]:53]), attempt 1 of 3 2025-07-09 16:17:46,198 DEBUG [org.xbill.DNS.SimpleResolver] Sending B-7828b307e21458b6522a0ff968025a68.iso6523-actorid-upis.edelivery.tech.ec.europa.eu./A, id=49908 to udp/2a02:228:0:0:0:0:53:181:53 2025-07-09 16:17:46,201 DEBUG [org.xbill.DNS.NioClient] Starting dnsjava NIO selector thread 2025-07-09 16:17:46,206 DEBUG [org.xbill.DNS.Lookup] Lookup for B-7828b307e21458b6522a0ff968025a68.iso6523-actorid-upis.edelivery.tech.ec.europa.eu./A, id=49908 failed using resolver ExtendedResolver of [SimpleResolver [/[2a02:228:0:0:0:0:53:181]:53], SimpleResolver [/[2a02:228:0:0:0:0:53:182]:53], SimpleResolver [/80.232.93.176:53], SimpleResolver [/80.232.93.177:53], SimpleResolver [B-7828b307e21458b6522a0ff968025a68.iso6523-actorid-upis.edelivery.tech.ec.europa.eu/139.105.36.174:53], ExtendedResolver of [SimpleResolver [/[2a02:228:0:0:0:0:53:181]:53], SimpleResolver [/[2a02:228:0:0:0:0:53:182]:53], SimpleResolver [/80.232.93.176:53], SimpleResolver [/80.232.93.177:53]]] java.io.IOException: java.lang.InterruptedException at org.xbill.DNS.Resolver.send(Resolver.java:156) at org.xbill.DNS.Lookup.lookup(Lookup.java:580) at org.xbill.DNS.Lookup.resolve(Lookup.java:660) at org.xbill.DNS.Lookup.run(Lookup.java:678) at network.oxalis.vefa.peppol.lookup.locator.BusdoxLocator.lookup(BusdoxLocator.java:125) at network.oxalis.vefa.peppol.lookup.LookupClient.getServiceMetadata(LookupClient.java:78) at network.oxalis.vefa.peppol.lookup.LookupClient.getEndpoint(LookupClient.java:168) at network.oxalis.vefa.peppol.lookup.LookupClient.getEndpoint(LookupClient.java:174) at network.oxalis.ng.outbound.lookup.DefaultLookupService.lookup(DefaultLookupService.java:75) at network.oxalis.ng.outbound.transmission.TransmissionRequestBuilder.build(TransmissionRequestBuilder.java:204)

And at the end of the trace after multiple attempts: 2025-07-09 16:37:10,318 DEBUG [org.xbill.DNS.NioClient] dnsjava NIO selector thread stopped

I have tried a various of configurations without luck, none which changes the outcome. I can reach the edelivery.tech.ec.europa.eu url directly so it does not seem to be a network issue.

System information:

javac -version => javac 21.0.7
mvn -version => Apache Maven 3.5.0
oxalis-ng => 1.0.0 (Have also tried 1.1.0 and 1.2.0)

Edit: Solved, calling executorService.shutdownNow(); too early. When sending to itself, there is no delay, but with the SML lookup it closes the executor before it is completed.