https://en.wikipedia.org/wiki/UHF_CB
Type: Posts; User: Pengy
https://en.wikipedia.org/wiki/UHF_CB
That is a repeater channel. (476.4750)
Suggest you go to a general chat chan such as 10. Leave all ctcss off as it is only there to scramble for security really
What channel are you using?
If the other units are newish, like you say, then they are very likely to have ctcss. If you are not on the exact same channel settings, then you will only get a one way...
Are all units on the same ctcss setting?