Keenetic and multi-wan: how to listen on both interfaces?

Question

ZyXEL

Comrades, tell me please ...
there is Zyxel Keenetic with NDMS 2.x
, 2 providers are plugged into it. addresses:
1.1.1.1
2.2.2.2
when using 2.2.2.2 as the main one, there is no way to connect to 1.1.1.1 from the outside.
at the same time, the exit through 1.1.1.1 works ... those, I registered static routes to some resources, and everything seems to be okay ... But I also want to open some resources through 1.1.1.1, well, for example, rdp. That there was an administrative entrance on an alternative IP.
How can I activate 1.1.1.1?

Answer 1

partially answer the question here: https://help.keenetic.com/hc/ru/articles/360000033699
but this is not a very beautiful solution, as the server always uses a slower connection... in my case this is acceptable.