All 4 Uses

however
in
The Scorch Trials
(Edited)

By midnight, however, when Minho finally called on them to stop and get more sleep, the city and its now-burning fires ever closer, the wind had become even stronger.
p. 124.3 *

however = a word used to connect contrasting ideas as when using though, in spite of that, in contrast, nevertheless, etc.
Once inside, however, he didn't know what to do.
p. 152.5
He didn't mention Teresa, however—she was the only thing he left out.
p. 154.7 *

however = in whatever way
What Thomas did hear, however, gave him little hope.
p. 266.3

however = a word used to connect contrasting ideas as when using though, in spite of that, in contrast, nevertheless, etc.

Definitions:

(1) (however as in: However, complications may...)
though (or another expression that connects contrasting ideas)

Based on idea 1 we might not expect idea 2, but this is a way of saying that even though idea 1 exists, we still have idea 2. Synonyms include in spite of that, despite that, nevertheless, nonetheless, on the other hand, in contrast and but.
(2) (however as in: However much she tried...)
to whatever degree (regardless of how much; or whatever unspecified amount)
(3) (however as in: However you do it, get it done!)
in whatever way
(4) (meaning too rare to warrant focus)
Much more rarely (and arguably incorrectly), however can be used to intensify the word how, as when one says "However did you find her?" Grammarians would suggest using two words for that usage: "How ever did you find her?"