SIM7070G firmware and UDP

I have a DFRobot SimCom SIM7070G modem. It came with firmware 1951B15SIM7070 (from AT+CGMR). I thought I saw there was a new B17 firmware available, and loaded 1951B17SIM7080 till I realised my mistake and it is a 7080 firmware. I then wanted to back down to the original B15 and couldn't find it in downloads. I've downloaded and installed 1951B14SIM7070 OK, but I can't get UDP to work.
Is there somewhere I can download 1951B15SIM7070 from? Or a newer version?
For UDP, ideally I'd like to get a transparent UDP connection going with AT+CAOPEN and AT+CASWITCH, but even a non-transparent UDP connection would be OK. I always get +CAOPEN: n,1 for the CAOPEN reply, which is an error (2nd number should be zero for success). Anyone else having trouble getting UDP going? I don't need GPS so I've set AT+CGNSPWR=0 as I had read that the 7070 can't do UDP and GPS at the same time, but powering off the GNS subsystem doesn't help unfortunately.
Best regards,
Andrew Tridgell
In [url=https://spacewavesgame.io/]space waves[/url], each level is made by hand, which makes it a unique test of your speed and accuracy.

I now have transparent UDP working with the SIM7070G. I am using firmware 1951B17SIM7080 and the following sequence from power on creates a working transparent UDP connection to IP aaa.bbb.ccc.ddd on UDP port 40001:
AT+CREG?
AT+CREG?
+CREG: 0,1
OK
AT+CACID=0
AT+CACID=0
OK
AT+CNACT=0,1
AT+CNACT=0,1
OK
+APP PDP: 0,ACTIVE
AT+CAOPEN=0,0,"UDP","aaa.bbb.ccc.ddd",40001
AT+CAOPEN=0,0,"UDP","aaa.bbb.ccc.ddd",40001
+CAOPEN: 0,0
OK
AT+CASWITCH=0,1
AT+CASWITCH=0,1
OK
CONNECT
test message
test reply

What is the power supply that you're using to power up SIM7070G?

I've tested with 5v, 12v and 6v. Also tested with USB power.