Restarted second site - everything running smoothly since, no errors, all devices with their original assigned IPs etc.

@MR.S ER8411 both sites

@MR.S Well , yes and no. I tried several things, including downgrading to 5.13 (incl. uninstalling without removing pers. data and with removing pers. data and re-installing from scratch plus...

@Clive_A Oh, my bad. Had already opened all ports in the firewall incl. a proper NAT, but -after your mail - checked again and found a typo in one port number. Works now, thanks for the product! Br's

@MR.S Not here. In contrary - messed up with 2FA..... Think will need to travel to the remote site and restart the router.. Thanks & Br's

@MR.S Thx! Also use the ER 8411 as router. No problems on the local site, i.e. where the controller sits, but the other site is completely offline. At least I do not have access to any device there....