I have T-MOBILE 5G Home Internet.
I have a Cisco 3560. I have a few VLANS, my main vlan is 108.

interface Vlan108
 description DUNCARRICK-NETWORK
 ip address 192.168.8.245 255.255.255.0

I have a bunch of ports in access mode in vlan 108. PCs get IPs on 192.168.8.0/24 with .245 as the gateway.

The traffic then goes out port Gi0/1.

I have a default route

ip route 0.0.0.0 0.0.0.0 192.168.100.1

interface GigabitEthernet0/1
description SWITCH-TO-TMOBILE-LINK
no switchport
ip address 192.168.100.2 255.255.255.0

it goes to the TMobile gateway, 192.168.2.1.

All works well.

I just added Astound broadband. So before I get rid of my Tmobile I want the Astound to work the same way.

I configured port 24.

interface GigabitEthernet0/24
 description SWITCH-TO-ASTOUND
 no switchport
 ip address 192.168.0.2 255.255.255.0

I removed the default route and added a new one:

ip route 0.0.0.0 0.0.0.0 192.168.0.1

The Astound router is a CODA-5712 (1B) and its IP is 192.168.0.1

The Astound device kinda sucks. It wont allow me to add a /24 return route to the switch, so I add a bunch of single IPs.

destination IP 192.168.8.245 : Gateway  192.168.0.2
destination IP 192.168.8.157 : Gateway  192.168.0.2

etc, etc ….. From a PC on VLAN 108 I cannot ping 8.8.8.8.

From the switch, ping 8.8.8.8 works.
But ping 8.8.8.8 source vlan 108 does not work.

From the PC a trace to 8.8.8.8 shows :
192.168.8.245
192.168.0.1
and then stops there. So I do get to the astound device.

From the astound device I can ping the PC (.157) and any other IP for which I added a return route.

I looked on the Astound device, I couldn’t find any other relevant config options, like NAT.

I feel that my VLAN is somehow not being NATted by the Astound device.
Of course if I join the Astound wifi or plug a cable from the PC into the Astound, I get a 192.168.0 address and that works just fine to the internet.

So in summary, no major changes to the switch, just a new default route pointing to the Astound instead of the TMobile.

Any ideas?

Thanks very much.