Devices on two separate NIC cards can't find each other

[taysseerk]

I have a OPNSense installed on a Dell workstation. I have the On Board NIC configured as the WAN port, and two separate NIC cards for extra ports. The first NIC card has 2x 2.5 Gigabit Ethernet RealTek RTL8125 ports, and the second NIC card is a 4x 1 Gigabit HP NC364T card.

I created a bridge and added both 2.5G and 4 1G ports from both cards to it. I set the LAN to 192.168.85.0/24 on the bridge. I also created a DHCP server on that same bridge.

Problem I've found is devices on one of the NICs can not truly find devices on the other NIC. It happens both ways. Devices individually get DHCP IPs and Internet successfully, but the devices on one NIC can not fine devices on the other NIC. IP scanners do pick up the devices, but do not see any open ports, so unsure how they're getting picked up in the first place.

For troubleshooting I verified that hardware offloading was disabled and I also turned on promiscuous mode on all the ports involved, including the bridge, but to no avail. I could not get these devices to ping, RDP or SSH into each other. I also verified that Firewall rules is set to any-to-any across the subnet.

Does anyone know why this would happen in the first place? Any other ideas to troubleshoot this?

Thanks

**EDIT**
I'd like to update something. After some troubleshooting I found that even if two devices are on two ports of the same NIC, they still can't communicate to each other. I can only get my network to communicate if I pick one of the NIC ports and run it to an unmanaged Gigabit switch and then put all my devices on that switch as well. Only then will everything work.

I still want to be able to plug into the other ports and have them communicate just as well. I still don't know what I'm doing wrong.

[Patrick M. Hausen]

Did you set the two tunables as documented?

https://docs.opnsense.org/manual/how-tos/lan_bridge.html

[CJ]

Second what pmhausen asked.  It's probably the tuneables missing.

That said, is there a reason you want to bridge them all together instead of using a switch?  STH has a bunch of cheap 2.5g switches that they've been reviewing lately.  Some are even managed.  This would also reduce the performance penalty of OPNSense routing the traffic.