DDNS IP different from whatismyipaddress IP leads to wg problem

Not on Ryanair!
Just a check on the basic network layout: the Huawei 4g router is, is mapped via Mac address to the OpenWrt router with that used as the static wan address. The OpenWrt LAN is which is what I put in the wireguard app DNS field. Is there an obvious mistake in this?

Back now, here is the output of ifconfig eth0.1 whic looks OK

root@OpenWrt:~# ifconfig eth0.1
eth0.1    Link encap:Ethernet  HWaddr BC:AE:C5:C4:B2:A7
          inet addr:  Bcast:  Mask:
          inet6 addr: fd48:3fe9:fba1:3700:beae:c5ff:fec4:b2a7/64 Scope:Global
          inet6 addr: fe80::beae:c5ff:fec4:b2a7/64 Scope:Link
          RX packets:23720 errors:0 dropped:3114 overruns:0 frame:0
          TX packets:4089 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:4315723 (4.1 MiB)  TX bytes:704816 (688.2 KiB)

I think I'll update to 18.06.04 and start with a blank slate!