Allowed IPs: the 0.0.0.0/0 is from just having the tunnel, before applying the fixes. I have used 0.0.0.0/1 + 128.0.0.0/1 there as well before with no detectable change in functionality.
Here is what I have post-editing in terms of allowed IPs:
Here is the section of /etc/config/mwan3 I added, together with a bit of what was there for reference:
…and here is the /etc/mwan3.user
(sorry, here is the table/wgname bit as well, missed that above:)
