DHCP on eth1 interface only

I have the er-lite 3.

eth0 - WAN
eth1 - LAN 1 (192.168.10.70)
eth2 - LAN 2 (192.168.0.79)

LAN 1 is our network. LAN 2 is the network of a company we share our office with which is connected so we can use the printers in the office.

Today the whole LAN 2 had a bit of a melt down. Cause yet to be determined but having only just connected the set up as described above a couple of days ago, I am naturally slightly concerned that our router may be the cause.

The router is also our DHCP server for LAN 1 serving in the range 192.168.10.80-250. There seems to be no way of defining which interface you want the DHCP server to work on.

Is there a chance that there has been a DHCP server clash caused by our router serving a conflicting range of IP addresses to the DHCP server on LAN 2?

Thanks in advance for any assistance. I am most definitely a novice so apologies if this is really basic stuff!