I just got an Edge 1040 (non-solar), applied all of the software updates etc. I now have version 17.26 and have tested that with the issue below too.
I previously had an Edge 530 and never had any connection issues with my Di2 bikes however I have immediately encountered issues with the 1040 and one of my bikes.
With one of my bikes I have no issues, using a Di2 system with a wireless unit EW-WU111 (firmware version 4.6.0), this bike works exactly as it did with my old Edge 530, e.g. gear display works fine, toggling screens using assigned shifter buttons and front shift alerts in synchroshift mode.
However my second Di2 bike which uses a Shimano SC-MT800 Display (firmware version 4.6.0) for wireless connection, will connect but infrequently updates the gear position datafield, very rarely responds to screen toggling, and rarely warns of front shifts in synchroshift mode, it also loses connection very frequently during rides (every couple of minutes or so).
I have ensured that my Di2 systems and Edge are all up to date on the latest firmware but the issue persists.
It seems strange that this would happen given that I have had zero issues with these connections on my Edge 530 which always worked seamlessly with page scrolling via the shifters being very responsive. I was wondering if anyone has had similar issues and if they knew if there is a way to resolve this?
I am currently debating whether to return my Edge 1040 due to this, as I rely heavily on being able to switch screens from my Di2 shifters and feel that having this issue makes the 1040 into a bit of downgrade for me.