Turned out to be my fault,  as I expected. The vlan25 static route on the meraki was pointed to the meraki interface address (..35.254) rather than the one on the dell core sw (...35.1).   Thanks for helping me narrow this down
Hi, Sorry, but its been 12 years since I've built a totally new network, so perhaps I'm just being stupid. FIrst: here is my setup: I'm replacing a largely obsolete network which has been hacked together for the last 20 years with a new paralell network based on S- series switches with core and internal routing being handled by an S5232F-ON with mostly S-5148F-ON on the edge. I have 3 Vlan's  (15,25,35) and all are assigned IP's only on the S5232F of 192.168.15.1, ...25.1. ....35.1.   35 is for my servers and is my gateway L3.  all of the S5148 and a few others are connected via 100G trunk's to the S5232.  DHCP for this network is a ADDC at 192.168.35.10.  All this seems to be working fine.  The machines on VLAN25 see and receive dhcp from the machines on VLAN35 just fine.   I have a Legacy Cisco MX-250 Meraki Cloud controlled appliance which is being used as a router for the existing legacy network as well as a gateway to the internet..  That network, which includes Nseries Dell Switches,  is functioning as expected. MY PROBLEM: I have one port ( 1/1/1:1) on the S5232F setup as a trunk  allowing Vlan 35 into the Meraki. On the Meraki.  the Meraki,  (which has no command line) is set to allow all VLAN's on this trunk port and has an L3 address of 192.168.35.248. And a nateive vlan of 1 On the S5232F,  I have a route of “ ip route 0.0.0.0/0 192.168.35.254 “. The Meraki is acting as a internet gateway,  for the legacy network and hopefully also for this new network. All machines on vlan 35 can reach all machines on the Legacy Network and the Internet via the Meraki Trunk port.  All machines on the Legacy network can reach all machines on Vlan 35.  Machines on VLAN 25,  which at the moment is the only other Vlan with any machines on it, can reach all addresses on VLAN35, except the 192.168.35.254 on the meraki. I setup a static route on the meraki to 192.168.25.0/24 via 192.168.35.254 and machines on the Legacy Network can now ping addresses on Vlan 25 .     Question: Why can only Vlan 35 reach the external networks and internet,  and how do I fix it?   S5232F-ON relevant config:   ! Version 10.5.2.7 ! Last configuration change at Feb  24 21:18:57 2022 ! ip vrf default ! interface breakout 1/1/1 map 10g-4x interface breakout 1/1/2 map 100g-1x ……………………….. iscsi target port 860 iscsi target port 3260 system-user linuxadmin password **** hostname coresw001 username admin password **** role sysadmin priv-lvl 15 aaa authentication login default local aaa authentication login console local ! class-map type application class-iscsi ! policy-map type application policy-iscsi ! interface vlan1  no shutdown ! interface vlan15  vlan-name AdminDevices  description vlan15  no shutdown  ip address 192.168.15.1/24  ip helper-address 192.168.35.10 ! interface vlan25  vlan-name AudiosDatNetwork  description vlan25  no shutdown  ip address 192.168.25.1/24  ip helper-address 192.168.35.10 ! interface vlan35  description Servers  no shutdown  ip address 192.168.35.1/24 ! …………………………………… ! interface mgmt1/1/1  no shutdown  no ip address dhcp  ip address 192.168.50.210/24  ipv6 address autoconfig ! interface ethernet1/1/1:1  description "Uplintk to MX-250"  no shutdown  switchport mode trunk  switchport trunk allowed vlan 25,35  flowcontrol receive off ! …………….. ! interface ethernet1/1/31  no shutdown  switchport mode trunk  switchport trunk allowed vlan 15,25,35,45,55,65  flowcontrol receive off ! interface ethernet1/1/32  no shutdown  switchport mode trunk  switchport trunk allowed vlan 15,25,35,45,55,65  flowcontrol receive off ! ……………………. ! ip route 0.0.0.0/0 192.168.35.254 ! snmp-server contact "Contact Support" !   S5148F-ON config: ! Version 10.4.3.8 ! Last configuration change at Feb  17 02:39:49 2022 ! ip vrf default ! interface breakout 1/1/49 map 100g-1x interface breakout 1/1/50 map 100g-1x interface breakout 1/1/51 map 100g-1x interface breakout 1/1/52 map 100g-1x interface breakout 1/1/53 map 100g-1x interface breakout 1/1/54 map 100g-1x hostname edgesw002 system-user linuxadmin password $6$5DdOHYg5$JCE1vMSmkQOrbh31U74PIPv7lyOgRmba1IxhkYibpp MXs1KM4Y.gbTPcxyMP/PHUkMc5rdk/ZLv9Sfv3ALtB61 iscsi enable iscsi target port 860 iscsi target port 3260 username admin password $6$q9QBeYjZ$jfxzVqGhkxX3smxJSH9DDz7/3OJc6m5wjF8nnLD7/VKx8SloIh p4NoGZs0I/UNwh8WVuxwfd9q4pWIgNs5BKH. role sysadmin priv-lvl 15 aaa authentication login default local aaa authentication login console local ! class-map type application class-iscsi ! policy-map type application policy-iscsi ! interface vlan1  no shutdown ! interface vlan15  no shutdown ! interface vlan25  no shutdown ! interface vlan35  no shutdown …………. ! interface mgmt1/1/1  no shutdown  no ip address dhcp  ip address 192.168.50.212/24  ipv6 address autoconfig ! interface ethernet1/1/1  no shutdown  switchport mode trunk  switchport trunk allowed vlan 15,25,35,45,55,65  flowcontrol receive on ! interface ethernet1/1/2  no shutdown  switchport access vlan 25  flowcontrol receive on ! ……………………… ! interface ethernet1/1/54  no shutdown  switchport mode trunk  switchport trunk allowed vlan 15,25,35,45,55,65  flowcontrol receive on ! support-assist snmp-server contact "Contact Support"  
S series OS10 Switches and CIsco Meraki Firewall, L3 Vlans can't see gateway