How to connect a second router to a router distributing Internet with a hidden SSID, which will distribute free WIFI?

Question

WiFi

There is a router with a hidden SSID and a dynamic IP on which the connections of all my personal devices live. Everything is fine, but it is tiring to manually enter the connection settings for each guest. I found a second router with DD-WRT, now I want to make the Internet for friends, guests, passers-by. I'm paranoid, but not miserly) The
question is, how can I connect the second router to the first so that I can take the Internet from a hidden point and distribute it on the second one without a password?

Answer 1

Solution number 1:
Stupidly connect with a wire.
Change the routers to one adequate.

Answer 2

And what for such difficulties, connect with a ddwrt cable, and cut the speed of the public