How to set up a router with OpenWRT as a switch + transmission?

Question

linux

Hello!
What we have:
1 router as the main gateway to the Internet and a DHCP server.
2 router connected to the first cable (on the first router in LAN - on the second in WAN).
What has been done on the 2nd router:
Installed OpenWRT firmware, connected an external HDD, installed Transmission, DLNA server, etc.
The WAN interface was removed in the settings, only one vlan was left (including all ports of the router), dhcp was disabled, a static ip was registered from the subnet of the 1st router.
When connected to the 2nd router, both via cable and WiFi, the Internet works fine everywhere, the entire home network works without issues, movies are played via dlna from the HDD.
BUT
On the 2nd router, access to I-no for its own services does not work: Transmission does not download or distribute files, the software update on the router does not work (opkg_download: Failed to download) ...
Please tell me how to make Transmission download and distribute all :)

Screenshots

Answer 1

DNS not specified

Answer 2

On the second router in the settings, change the broadcast address to 192.168.100.255 and add DNS 192.168.100.1.