@smalacar The maximum value of a uint16 is 65535, which if it is in milliseconds would be 65.5 seconds ~ It does seem like the code for the example might be limited in functionality ;)
10 Minutes might be too long for the internal timer for the advertisement; You could try using a software timer, a hardware timer, or the WDT to turn on advertisement for a single packet every ten minutes instead of setting the advertisement interval. I think this would be a more likely-to-succeed approach.
According to the BLE spec, the maximum advertising interval can be set up to 10.24s. Thus 10 minute advertisement interval violates the spec you can't set it directly.
Also 10 minute advertisement interval is too long such that your Central will not be able to find the peripheral so fast.
Please let us know why do you want to keep such long adv interval. If your application needs advertising slow, you can keep adv timeout less. And after a 10 minute timer, you can start the advertisement again.