- Press Shift+F12 to open the strings window
- Press Ctrl+F and search ConnectingMessage, make sure to enable Unicode C string support in the setup window.
- Go to the string and xref it (by pressing on it and clicking X).
- The disassembly should look similar to this:

.text:0000000002F4E639 mov rbx, [rdi] ; jumptable 0000000002F4E5B1 case 4
.text:0000000002F4E63C lea r9, aConnectingmess ; "ConnectingMessage"
.text:0000000002F4E643 lea r8, aGameviewportcl ; "GameViewportClient"
.text:0000000002F4E64A lea rdx, aConnecting_1 ; "CONNECTING"
.text:0000000002F4E651 lea rcx, [rsp+0B8h+var_58]
.text:0000000002F4E656 call sub_1F43840
.text:0000000002F4E65B mov rcx, rax
.text:0000000002F4E65E call sub_1F5CE20
.text:0000000002F4E663 mov r8, rax
.text:0000000002F4E666 mov rdx, rsi
.text:0000000002F4E669 mov rcx, rdi
.text:0000000002F4E66C call qword ptr [rbx+2E8h]
.text:0000000002F4E672 mov rdi, [rsp+0B8h+var_50]
.text:0000000002F4E677 jmp loc_2F4E703

- Here is the source code for comparision (GameViewportClient.cpp):

case ETransitionType::Connecting:
DrawTransitionMessage(Canvas, NSLOCTEXT("GameViewportClient", "ConnectingMessage", "CONNECTING").ToString());
break;

- Here is a signature from Fortnite 9.41, it may work on other games as well so give it a try:
"48 89 74 24 ? 57 48 81 EC ? ? ? ? 80 B9 ? ? ? ? ? 48 8B F2"