#include <StringConstants.au3> ; to declare the Constants of StringRegExp
#include <Array.au3> ; UDF needed for _ArrayDisplay and _ArrayConcatenate
Local $sRegex = "(?m)Error\s+in\s+heartbeat\s+\(requestId:\s+\d+\)\s+to\s+(?<mongo>[^:]+)"
Local $sString = "{"time":"2020-07-24T11:48:21.18957143Z","event":"2020-07-24T11:48:21.189+0000 I REPL_HB [replexec-949] Error in heartbeat (requestId: 649360) to mongodb3:27017, response status: NetworkInterfaceExceededTimeLimit: Couldn't get a connection within the time limit\n","hostname":"node2"}"
Local $aArray = StringRegExp($sString, $sRegex, $STR_REGEXPARRAYGLOBALFULLMATCH)
Local $aFullArray[0]
For $i = 0 To UBound($aArray) -1
_ArrayConcatenate($aFullArray, $aArray[$i])
Next
$aArray = $aFullArray
; Present the entire match result
_ArrayDisplay($aArray, "Result")
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm