Hi , I am having trouble getting wireguard working, I believe it stems from incorrect hostname setup

I have dual wan,
1st gets am ip from its router running cgnat so not suitable for vpn
2nd is static ip pppoe and gets a /32 address

when I set host name to ip from external interface it grabs the cgnat dynamic ip which wont pass wireguard.

when I set use hostname and get a ut.1**.23*.10*.20* address , I get a pharse error in wireguard when I try to capture the barcode.

I tried the manually specificed address with my external Ip and no joy there either, I also have a ddns setup with duck and it grabs the wrong ip also,

Is there anyway to set my 2nd pppoe as the default external interface

Or is there something else Iam missing ,

Thanks Jeremy