I have had this issue since upgrading my internet connection to 2.0Gbps

Glad you got it working. Be sure to save off a back up configuration to file for safe keeping. Saves time if a reset is needed.
https://kb.netgear.com/24231/How-do-I-back-up-the-router-configuration-settings-on-my-Nighthawk-router
Enjoy. 📡

Follow-up, DCHP issue occurs with port mirror on switch turned off. Logs and Wireshark for the DHCP failure below.

RAX200 Log
[Internet connected] IP address: 192.168.0.100, Tuesday, Jan 30,2024 13:11:47
[Time synchronized with NTP server] Tuesday, Jan 30,2024 13:11:43
[Internet disconnected] Tuesday, Jan 30,2024 13:11:42

ER707-M2 Log
2024-01-30 13:11:42 dhcp_server[23979]: <5> 01712251 DHCP Server allocated IP address 192.168.0.100 for the client[MAC: 6c:cd:d6:ea:cb:9a].
2024-01-30 13:11:41 dhcp_server[23979]: <5> 01712251 DHCP Server allocated IP address 192.168.0.100 for the client[MAC: 6c:cd:d6:ea:cb:9a].
2024-01-30 13:11:39 dhcp_server[23979]: <5> 01712251 DHCP Server allocated IP address 192.168.0.100 for the client[MAC: 6c:cd:d6:ea:cb:9a].
2024-01-30 13:11:35 dhcp_server[23979]: <5> 01712251 DHCP Server allocated IP address 192.168.0.100 for the client[MAC: 6c:cd:d6:ea:cb:9a].
2024-01-30 13:11:28 dhcp_server[23979]: <5> 01712251 DHCP Server allocated IP address 192.168.0.100 for the client[MAC: 6c:cd:d6:ea:cb:9a].
2024-01-30 13:11:14 dhcp_server[23979]: <5> 01712251 DHCP Server allocated IP address 192.168.0.100 for the client[MAC: 6c:cd:d6:ea:cb:9a].

Wireshark(RAX200 WAN port)
39 13:11:14.014065 0.0.0.0 255.255.255.255 DHCP 590 DHCP Request - Transaction ID 0xcd407536
40 13:11:14.015114 192.168.0.1 192.168.0.100 DHCP 343 DHCP ACK - Transaction ID 0xcd407536
41 13:11:28.046965 0.0.0.0 255.255.255.255 DHCP 590 DHCP Request - Transaction ID 0xcd407536
42 13:11:28.047821 192.168.0.1 192.168.0.100 DHCP 343 DHCP ACK - Transaction ID 0xcd407536
43 13:11:35.064837 0.0.0.0 255.255.255.255 DHCP 590 DHCP Request - Transaction ID 0xcd407536
44 13:11:35.065475 192.168.0.1 192.168.0.100 DHCP 343 DHCP ACK - Transaction ID 0xcd407536
45 13:11:39.083686 0.0.0.0 255.255.255.255 DHCP 590 DHCP Request - Transaction ID 0xcd407536
46 13:11:39.084780 192.168.0.1 192.168.0.100 DHCP 343 DHCP ACK - Transaction ID 0xcd407536
47 13:11:41.102505 0.0.0.0 255.255.255.255 DHCP 590 DHCP Request - Transaction ID 0xcd407536
48 13:11:41.103853 192.168.0.1 192.168.0.100 DHCP 343 DHCP ACK - Transaction ID 0xcd407536
49 13:11:42.166514 0.0.0.0 255.255.255.255 DHCP 590 DHCP Discover - Transaction ID 0x98dbee39
50 13:11:42.169556 192.168.0.1 192.168.0.100 DHCP 343 DHCP Offer - Transaction ID 0x98dbee39
51 13:11:42.178720 0.0.0.0 255.255.255.255 DHCP 590 DHCP Request - Transaction ID 0x98dbee39
52 13:11:42.181819 192.168.0.1 192.168.0.100 DHCP 343 DHCP ACK - Transaction ID 0x98dbee39

And this is with the following wire configuration? 

CM Modem>MS Switch<>RAX200 using it's MG port from the switch? 

 CM Modem>ER707>MS Switch<>RAX200 using it's MG port from the switch? 

 ER707-M2 is the DHCP server/firewall. Yes, MG port on RAX200. Pi4 (2.5G) is also on the MS switch (file server for file transfer test once per minute), also traffic monitor. Wireshark is from Mini PC with RAX200 MG WAN port mirrored via MS switch to Mini PC 2.5G (DHCP capture filter).

Yes, it's for traffic monitoring.

Would be interesting to see since you have DCHP/Firewall at the switch, put the RAX in to AP Mode using it's MG port. 

If you have DHCP and firewall infront of the RAX, then possible your configuration would not work and is not really supported. Or something is happening between the switch and the RAX. Average home configurations don't have this configuration with the managed switch and router in router mode. The RAX router would be in AP mode if there is DHCP and firewall in between the ISP service and any wifi router system. 

I believe AP mode disables Armor Bitdefender. I could test with RAX200 MG port connected to Modem and see if disconnect QoS symptom occurs, but I can't monitor traffic with that config.

Lets see if we can get some NG Switch people to review this which is why I asked for this to be moved here. 
Seems that there maybe a configuration issue at the switch that should be looked at. Monitoring traffic with a switch before the router may have some impact on how the router after the switch is performing. Yes, Normal home configurations for this model router is mainly connected to the ISP modem directly with out any switch device in between them, which is for all intents and purposes, is how NG designed these to work. Have someone help you with the configuration workings of the switch and any flow control features that maybe needed. 

Hopefully NG can review this and help you out. 

BrianL ErwinL ReneD 

Good Luck.

In theory it should be able to work no matter what the upstream gateway is, and the two other devices on the switch have no issues that I know of. Also, double NAT is only an issue if you want to initiate a connection from the internet which is exactly what I want to prevent. I would point out the flurry of DHCP requests and ACKs before the disconnect as suspicious. Note that the MG port is clearly getting ACKs from the DHCP server. I have the pcap file if you want it.

Figure 1 is my traffic monitoring configuration.

https://media.defense.gov/2022/Jun/15/2003018261/-1/-1/0/CTR_NSA_NETWORK_INFRASTRUCTURE_SECURITY_GUIDE_20220615.PDF

JamesL1979 

Very curious about one statement you made.

You mentioned that the RAX200 disconnection problem started when you upgraded to 2Gbps AND you replaced the cable modem ?

In other words, RAX200 never dropped the WAN connection or had problems renewing the ip address before the replacement/change of the cable modem?.

Do you have DHCP enabled on the cable modem?  if yes what is the DHCP scope?

What is the ip address assigned or leased on the ER707-M2 port connected to the cable modem?

What is the DHCP scope configured on the ER707-M2?

I had the same topology before but all 1G. I had a T25 modem, TL-R600VPN router, GS105Ev2 switch, and RAX200 connected via the 1G internet port. Comcast said my T25 not supported any longer and I should upgrade to CM2050V. Before this I would get maybe 200-300Mbps on Google Speed test and I thought that must be what my tear was, should be enough. I checked my tear and it was Extreme Pro which is supposed to be 800Mbps, so I tried upgrading since the new modem is supposed to support Gigabit+, but I'm still getting 200-300Mbps on the LAN connected PC. By this time I have connected 2.5Ge Mini PC directly to the modem to verify internet connection is good. I started upgrading all the downstream hardware to 2.5Ge and I noticed the RAX200 has 2.5Ge option for internet, but still only 200-300mbps from the LAN side.

The CM2050V doesn't have a router, it's managed by Comcast from the headend, they update the firmware, provision, etc..

The ER707-M2 has a public routable WAN IP assigned by the Comcast DHCP server.

The ER707-M2 has a private not routable LAN IP 192.168.XX.XX mask 255.255.255.0.

The RAX200 has a reserved, fixed "WAN" IP it got via DHCP from the ER707-M2 before it was made fixed/reserved.

The RAX200 has a different (subnet) private not routable LAN IP 192.168.XX.XX mask 255.255.255.0. 🙂