@ mod's:
Thanks to both for "moderating".
As my converted Plusnet Hub One could possibly be put into service in router mode only as I would retain my trusty 1312-B10A as modem and to preserve line stat's monitoring via RPi, suppose still on topic really.
@ Alex Atkin UK:
Well done on your HH-5A & PN Hub One OpenWRT conversions, as a very much hands on maintenance tech. all my working life dating back to the pre "large scale integration" days when repair to component level was still an option, certainly no stranger to PCB soldering, however, equiped with a temp. controlled Weller soldering station & iron with very small tip, still struggled under the magnifying glass to make the 4 connections required and was very surprised that the serial interface actually worked first time.
Unfortunately, unlike experience, eye sight does not improve with age !
Took much longer to successfully install the FW packages, as they are very much sequential had to return to the start quite a few times after making implementation errors, as you have said, should be much easier the second time around.
Making the serial header & reset connections available without having to open the case again is probably over kill, just didn't wish to de-solder the 4 cables from the PCB again and possibly bridge some pads or damage the tracks.