@user91 The algorithm is hard coded in the FW for sure. I would try the following as well: Set the default servers I posted earlier and switch the '24-Hour Time' ON just for the experiment. If still...

@user91 Disabling SPI Firewall won't affect this behavior. There are several servers behind the time.nist.gov domain - https://tf.nist.gov/tf-cgi/servers.cgi Here's a screenshot from my PC pinging...

@Klemen You can set the same SSID for all APs, but I would set them different (with same wireless passwords on each AP), so I can determine to which AP I am connected to by its SSID (e.g. AP1, AP2,...

@OliviaRaz You can't according to this official statement.

@user91 Just out of interest what's your output here:

@mantecon2030 Which LAG mode you've set up on NAS side ? Try Balance XOR. Here's a guide for configuring the Synology NAS LAG. Here's a guide for configuring the router LAG.