D735 web interface error in sub menues

I have just added two used D735 to my set of otherwise perfectly-working D735. I updated the firmware at first to 10.1.169.13 and had the phones provisioned like all the others of my set. It looked fine at first but then I realized that some menus of the web interface keep on throwing errors: For example if I press the next page button in the directory to show the second page of my currently 82 contacts, I should be directed to the page http://x.x.x.x/adr.htm?next_tbook_pos=20 but get a browser error instead (connection interrupted). This is independent of the browser and happens on both phones. I tried factory reset and updated one in the suggested two steps to 10.1.184.14 - same problem. It is not only the directory but also for example the Preferences/Appearance/More Controls (to change the wallpaper) page gives the same error. I am running out of ideas. Does anyone have suggestions what else to try?

Thanks,

  LX