I don’t think what you’re trying to do is very practical.
For US 915, there are between 52 (SHORT_TURBO) and 208 (LONG_SLOW) frequency slots. Each node has to use the same modem presets as well as the same frequency (you can’t mix and match any of those). Nodes can only operate in one mode and frequency at a time.
So to cover all cases, you’d need:
- 52 nodes operating in SHORT_TURBO mode
- 104 nodes operating in SHORT_FAST
- 104 nodes operating in SHORT_SLOW
- 104 nodes in MEDIUM_FAST
- 104 in MEDIUM_SLOW
- 104 in LONG_FAST mode
- 208 in LONG_MODERATE mode
- Plus another 208 in LONG_SLOW mode
Source for those counts
That’s a total of 988 nodes to cover all, and that’s not even getting into the fact that they’d be talking over each other.
Basically, if you want to be a generic repeater, it’s best to set your custom channels as primary (if you want to have custom channels) and create a LongFast secondary channel. Then manually set your radio frequency to the one used by the default LONG_FAST setting (908.875 MHz).
That’s basically what I do and lets me have my own private channels while also relaying for and being able to make contact with anyone else using the default config.