INTER-VLAN ROUTING AND INTERNET NAT ISSUES

[TundeBakare]

i created an inter-vlan routing on a stick 1900 router. i have about 13 vlans. i configured another 1900 as nat router. the vlan is working and the hosts on different vlans are picking the normal ip from the dhcp server. but the issue is that their connection to internet is breaking. what i mean is that after configuring the nat, some hosts can browse internet while some cannot. the following day i discovered that all of the hosts cannot browse internet. since then i have been troubleshooting and the internet will come up and go.
please i need somebody to help me out. i am ready to provide further information base in the configuration.

 

[VinceWhirlwind]

So, all the VLANs are on subnets that are hosted by Router1? The DHCP server is on a subnet off this router? All hosts' default GWs are the VLAN interfaces for their respective subnets on this router?
You have a default route on this router pointing at Router2? You have a subnet in use between router1 & router2 (and nowhere else)?
No other subnet from router1 exists on router2?
Router2 has a default route pointing at your ISP?

Obviously seeing your configs would answer these questions.