Before i take it to the mechanic/friend who set it up, I figured I should ask the collective.

The setup is 11s Di2 Ultegra, I believe this is a mix of 1st and 2nd generation 11s. The junction box is external under the stem.

On today's ride, everything worked fine for a few miles...but then the FD stopped working properly. It was in the small ring, and an attempt to shift to the big ring was met by a "shudder" where the FD cage moves about 2mm towards the big ring, the servo motor seems to "try" to move a few times, and then the cage goes back to the original position. It will NOT shift to the large ring.

I can post a couple pics of the FD, i actually took a video of the action the FD takes but that cannot be posted.

Post it on youtube and link

I have no idea what the mechanics of the FD are. To me it sounds like something with stripped gear teeth. But I have no idea if there even use gears.

A possibility is the FD is meeting resistance when moving and stops trying to move after some attempts. Have you cleaned and lubed the FD recently. Maybe it is just bound up somehow.

Looks & sounds similar to yours.
Don't get your hopes up, he didn't "fix" the derailleur, he fixed the bike by replacing the derailleur.

I've never seen mine act like that. However I was wondering why you weren't turning the crank as you shifted.

What series is the FD? Have you ever used eTube? If so, connect it up and see if it tells you anything about it. At least the old version of eTube did a brief check of everything when it started up. But perhaps that was only a connection and firmware check. Haven't used the newer version of eTube.

I only have two hands. One to shift and one to hold the phone camera. But it won’t shift when crank turning. I am not optimistic but the whole di2 is a black box to me. I can’t use etube as this is an old generation di2 and I would need a dongle and other hardware which is over my area of expertise.

Is your mechanic friend connected with a shop that is a authorized Shimano dealer? It's always possible that Shimano might give you some help on a new FD for it. Though it does sound like all the stuff you put on was used at the time you got it. But who knows how they will be feeling if they don't get ask.

When this happens, in my experience, it is usually corrosion/other contaminants preventing the derailleur from moving properly. Give it a good clean (either leave the wire plugged in, or pull a dummy plug from the levers and place it in the port), then apply lubricant to the pivot points of the derailleur, including the motor linkage visible under the cover.

Make sure you use the plastic separation tool to remove/install wires, as they are quite fragile.

If it continues to misbehave, re-writing the firmware of the unit (a factory rest, of sorts) sometimes fixes them.

*edit* E-tube project software does have limited functionality through the plug-in charger that most of those generation 11-speed bicycles would have; if I recall correctly, it can perform updates/firmware rewrites, and normal configuration changes...but not error checks. You would not have received one of those chargers if it came with an external/removable battery.

Probably not relevant but are you sure the battery has an adequate charge? Riding my 12 speed Ultegra DI2 this weekend, the FD stopped shifting, but the RD still shifted. Ended up being a nearly dead battery. I guess it makes sense that the FD would require more power to move the chain than the RD.

Thanks for the comments. Battery fully charged. Friend is a one-man shop not official Shimano dealer. I can try some lube but feels like something in the servo/motor is jammed.

I cannot recall if the upper and lower limits to the derailer are set in the e-tube software, but it looks like a limit is set incorrectly and that’s what’s keeping g the derailer from moving where it should. Get the model number and then look in the setup directions. You will likely need the e-tube software to make settings. Hopefully the system has the BlueTooth unit so you can access settings

Terry at Bettershifting.com

This is what happens when the battery gets low.

So if it appears fully charged, something might be amiss with the connection, or the battery itself is somehow the culprit.

If something is jamming it physically, you could take the derailleur off or the crankset off and then see if it moves freely.

It also does that by design, to give you a heads-up to recharge.

Probably a red herring, but .... are you using syncrho-shifting (either intentionally, or because you accidently pressed the button on the jxn box)?

https://bettershifting.com/frequently-asked-questions/

cf: "My TT/Tri bike no longer automatically shifts the front derailleur"

It's not a low battery. The front derailleur keeps working as usual until the battery charge is down near zero -- the indicator light is flashing red.
Then it turns off the front derailleur, to allow the rear to keep shifting a little longer (supposedly about 50 rear shifts?)

That looks like an 8050 front derailleur. I replaced my 6850 front when one of the the metal linkage bars snapped, after 8 years and 33000+ miles. It still made a normal shifting noise, but just didn't move the cage, of course.
The 8050 has a sturdier, redesigned linkage and was a plug-and-play replacement. (But I did have some annoyances getting it aligned correctly -- that's tricky)

Pawel the Di2 GP can probably fix it, or give instructions on how to fix it.

Take a look at his Youtube channel, it has information on how to take the derailleur apart and put it back together again: https://www.youtube.com/@Di2_GP

He's in the UK and fixes derailleurs for people quite a lot... unfortunately he's had a little bike accident and is out of action for the next couple of weeks. Either way, I'd send him the video (email in youtube bio, or message him on instagram (di2_gp)

Thanks for the tip. However this type of repair is beyond my basic ability.

To finish up the thread, my friend/mechanic took a look at it and stated fairly firmly that the motor mechanism would not easily be repaired (see above if you are inclined) and we put a new gently used FD on and the system is back and working now.