|A typical setup for this should look as follows:|
highspeed modem >> router >> switches (both) >> clients
It sounds like you have the switches daisy chained:
router >> switch 1 >> switch 2
If your router has 4 LAN ports, its recommended you plug both switches into the router unless there is a specific reason for not doing so.
Try connecting both switches to the router's LAN ports, if possible, if not do let me know and we'll take a look at other things to troubleshoot.