Fair enough. I started out from the point that the current beta does not handle lost grid meter as I expected. I will move from serial to IP based communication and hope that my problem is solved.
Having said this, I do think that I am not the only one with recurring loss of grid meter. You will find more on this forum if you search.
So maybe there is a common denominator or root cause, and that may be EMI. Or a timing issue. A clue for finding the cause might be that it almost exclusively happens during charging in my case.