Hmmm, well, after thinking it over again, I decided to reboot into PCLOS and remove the firewall, then try again. This time it worked!
Don't like being online without a firewall, so switched it back on again from the CC, and it's still working!
Beats me - but it's nice to be online in linux, not W.
Thanks for your suggestions Steve, and for your fine input in the afore-mentioned post about UMTSmon.