More than one users[1][2] have reported that they are seeing odd timeout issues with HTTP(S) calls in their applications. Based on the discussion in those threads, I believe there are 2 issues here, one in Undertow and one in WildFly.

In Undertow, I believe there's a bug which when using HTTP 1.1, in some cases, ends up marking an in-progress request as timed out (based on the value set for no-request-timeout). Thread[1] has more details on how to reproduce such a case, but like I note in that thread, I don't think the cipher suites is what's causing this. I haven't found the time to create a simpler reproducible application for that one yet and I haven't yet created a Undertow JIRA for it.

In WildFly, I think the default value of 60 seconds for no-request-timeout on the HTTP(s) listeners, is arbitrary and even too low. IMO, this probably should default to -1 (i.e. no specific timeout) and let the users decide what value makes sense in their setup.

[1] https://developer.jboss.org/thread/279379
[2] https://developer.jboss.org/thread/279261