M4100-26G changes VLAN membership after reboot

Yes right, Maintenance\Upload\HTTP File Upload\Text Configuration in order to let you download the configuration file, from the switch standpoint.

Thank you for your patience here, and your screenshots alongside text configuration show the issue you're having: there is conflicting port VLAN configuration on some ports. To me this is due to the fact you used Switching\VLAN\Advanced\VLAN Trunking Configuration for some configuration, and Switching\VLAN\Advanced\VLAN Membership or Switching\VLAN\Advanced\Port PVID Configuration for some other configuration. For instance on your Port 1, you said earlier you were seeing VLAN1 and VLAN50 added to the Trunk Allowed VLANs in Switching\VLAN\Advanced\VLAN Trunking Configuration after reboot. I think VLAN1 was back because VLAN1 was still kept as (default) Native VLAN in Switching\VLAN\Advanced\VLAN Trunking Configuration. If the port Native VLAN for untagged traffic is VLAN1, VLAN1 got to be added to the trunk. For VLAN50, although I can't see it in your previous screenshots, this was likely because of conflicting configuration at that time in Switching\VLAN\Advanced\VLAN Membership. Other example, I see conflicting utilization of Port PVID and Port Tagging for your port 7 (interface 0/7) in your configuration file.

 I would recommend we only configure port VLANs "Access Ports, Trunk Ports and Native VLANs" in:

• Switching\VLAN\Advanced\VLAN Trunking Configuration

or, alternatively, not simultaneously, we configure ports VLANs "Untag modes, Tag modes and PVIDs" in:

• Switching\VLAN\Advanced\VLAN Membership, and Switching\VLAN\Advanced\Port PVID Configuration

The configuration file above has mixed up configurations, so we should restart from a clean sheet. Maybe you can perform a factory-default in Maintenance\Reset\Factory Default for this. Then only use one of these methods. One think to keep in mind: VLAN1 is enabled by default on all ports (Access Ports, or untagged mode), so it must be removed from trunks and other access ports when necessary.

Based on my understanding of what you want to achieve (please keep me honest here):

• Ports 1, 5 and 7 in trunk mode with only tagged VLANs 100,200,300 allowed and no native VLAN for untagged traffic
• Ports 2, 3, 4 and 6 untouched (so in access mode with untagged VLAN 1)
• Port 7 in access mode with untagged VLAN 50

Here's the configuration for both modes. Of course, you can use local console (CLI) as well.

• Switching\VLAN\Advanced\VLAN Trunking Configuration

interface 0/1
switchport mode trunk 
switchport trunk allowed vlan 100,200,300
exit 
interface 0/2
exit 
interface 0/3
switchport mode trunk 
switchport trunk allowed vlan 100,200,300
exit 
interface 0/4
exit 
interface 0/5
switchport mode trunk
switchport trunk allowed vlan 100,200,300
exit 
interface 0/6
exit 
interface 0/7
switchport mode access
switchport access vlan 50
exit 

• Switching\VLAN\Advanced\VLAN Membership, and Switching\VLAN\Advanced\Port PVID Configuration

interface 0/1
vlan participation exclude 1
vlan participation include 100,200,300
vlan tagging 100,200,300
vlan acceptframe vlanonly
exit 
interface 0/2
exit 
interface 0/3
vlan participation exclude 1
vlan participation include 100,200,300
vlan tagging 100,200,300
vlan acceptframe vlanonly
exit 
interface 0/4
exit 
interface 0/5
vlan participation exclude 1
vlan participation include 100,200,300
vlan tagging 100,200,300
vlan acceptframe vlanonly
interface 0/6
exit 
interface 0/7
vlan pvid 50
vlan participation exclude 1
vlan participation include 50
exit 

Regards,