@CUBENET TL-R600VPN has the setting for ping of death. But it's checked by default and cannot be disable.

If the IP packet is more than 65535 bytes or less than 64bytes, router will think it's Ping of death attack. The size of the packet doesn't meet the network rule. Some devices may not understand the...

@RicRey Firstly try to connect your server to your router, make sure that your router is working normally. Then check your router's IP adderss. If it's 192.168.0.1, it may conflict with TL-SG3216....

TXM431-SR should be able to work with T2600G-28SQ. I think T2600G-28SQ is released last year. And TXM431-SR has been released many year ago. So TP-Link may not update the information for TXM431-SR.

TL-R600VPN should supports up to 256 IP address. Unfortunately this router may not meet your requirements.

When you use TL-WR841HP, it can work normally. Did WR841HP use dynamic IP as well? If yes, please confirm if your ISP will identify your MAC address, I mean maybe consider whether need MAC clone.