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I administer a network that was designed and implemented by others. It has several VLANs for different device classes, and uses Aruba network gear. One of the subnets is for servers and was limited in scope by a 255.255.255.192 subnet mask. The default gateway for this VLAN is x.x.x.62. I have run out of addresses and need to expand the scope. I changed the subnet mask from to 255.255.255.128 and changed it on all static-assigned servers, the core switch and the DHCP server.

The systems all get the correct new IP information and all existing machines communicate just fine. Any new server with an ip address over .62 works fine for local traffic but will not connect to the Internet. DNS works properly, but the traffic is not passed from the core switch to the router.

I’ve checked and checked and can’t find anywhere that might be blocking traffic. Any ideas would be greatly appreciated.

6 Spice ups
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Are you routing on a layer 3 switch rather than the firewall? If so, then the firewall has static routes pointing back at the layer 3 switch. In that case those routes probably have the old subnets.

3 Spice ups
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+1 for a static route being a likely issue. Definitely explore that, given that you’re saying internal traffic is all fine.

1 Spice up
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What does you link look like between the core switch and router?

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Routing or NAT. Are you using static routing, dynamic routing, or a combination of both?

When you expanded the subnet, did you make sure that it doesn’t overlap with any other subnets?

Check firewall NAT and access lists. Can the servers ping the firewall?

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Didn’t catch the 1st post originally when I replied. Welcome to the community.

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Thank you all for your input. The routing is done by our firewall/router, which is a new Cisco Meraki device that was configured by a contractor. After checking the switch for routing information and finding that it forwards all traffic to the router, I checked the routing table and found that the static route for the server VPN did indeed have a /26 subnet specified. I changed it to /25 and now things are working properly.

Thanks for pointing me in the right direction. I appreciate everyone’s ideas.