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Post Reopened by Teun Vink
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George Moromisato
George Moromisato
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I20I have a server with a static IP address connected to a Comcast Business router (Cisco DPC3941B).

EDIT 27 May 182018: Added config settings

EDIT 27 May 2018 This might be relevant: Email not delivered over local wifi, delivered all other times

Perhaps the Cisco router does not support Hairpinning? But wouldn't that result in NO connection as opposed to a slow connection?

I have a server with a static IP address connected to a Comcast Business router (Cisco DPC3941B).

EDIT 27 May 18: Added config settings

20I have a server with a static IP address connected to a Comcast Business router (Cisco DPC3941B).

EDIT 27 May 2018: Added config settings

EDIT 27 May 2018 This might be relevant: Email not delivered over local wifi, delivered all other times

Perhaps the Cisco router does not support Hairpinning? But wouldn't that result in NO connection as opposed to a slow connection?

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George Moromisato
George Moromisato
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EDIT 27 May 18: Added config settings

ROUTER CONFIG
Router is set to defaults/factory settings except for what Comcast 
did to set up the static IP address, etc. Settings as follow:

Bridge Mode: Disabled
WiFi: Enabled (but not used)
DOCSIS Software Version: dpc3941b-v303r20421762-180419a-CMCST
Model: DPC3941B
Vendor: Cisco
Hardware Revision: 1.0
Processor Speed: 447.28 MHz
DRAM: 1048576 MB
Flash: 128 MB

Firewall
Disable Firewall for True Static IP Subnet Only: OFF
Disable Gateway Smart Packet Detection: ON
Disable Ping on WAN Interface: OFF

Firewall Security Level: Minimum
LAN-to-WAN: Allow all
WAN-to-LAN: Block IDENT (port 113)

Local IP Network
IP Address (IPv4): 10.1.10.1
Subnet mask: 255.255.255.0
DHCPv4 Server: Enabled
DHCPv4 Lease Time: 7d:0h:0m
Link Local Gateway Address (IPv6): fe80::481d:70ff:fede:dcc8
Global Gateway Address (IPv6): 2603:3024:1705:3c00:481d:70ff:fede:dcc8
Delegated prefix: 2603:3024:1705:3c00::/56
DHCPv6 Lease Time: 7d:0h:0m
IPV6 DNS: 2001:558:feed::1

WAN Network
Internet:Active
Local time:2018-05-26 14:11:06
System Uptime: 4 days 16h: 56m: 42s
WAN IP Address (IPv4): 50.242.89.126
WAN Default Gateway Address (IPv4): 24.5.176.1
WAN IP Address (IPv6): 2001:558:6045:bf:31e4:2d63:9158:8238
WAN Default Gateway Address (IPv6): fe80::201:5cff:fe65:4c46
Delegated prefix (IPv6): 2603:3024:1705:3c00::/56
Primary DNS Server (IPv4): 75.75.75.75
Secondary DNS Server (IPv4):75.75.76.76
Primary DNS Server (IPv6):2001:558:feed::1
Secondary DNS Server (IPv6):2001:558:feed::2
WAN Link Local Address (IPv6): fe80::4a1d:70ff:fede:dcc7
DHCP Client (IPv4):Enabled
DHCP Client (IPv6): Enabled
DHCP Lease Expire Time (IPv4): 2d:10h:53m
DHCP Lease Expire Time (IPv6): 2d:17h:59m

Managed Sites: Disabled
Managed Services: Disabled
Managed Devices: Disabled
Port Forwarding: Disabled
Port Triggering: Disabled
True Static IP Port Management: Disable all rules and allow all
   inbound traffic through
Remote Management: Disabled
DMZ: Disabled
NAT: Disable All
Static Routing: None
Dynamic DNS: Disabled
Device Discovery: Disabled

EDIT 27 May 18: Added config settings

ROUTER CONFIG
Router is set to defaults/factory settings except for what Comcast 
did to set up the static IP address, etc. Settings as follow:

Bridge Mode: Disabled
WiFi: Enabled (but not used)
DOCSIS Software Version: dpc3941b-v303r20421762-180419a-CMCST
Model: DPC3941B
Vendor: Cisco
Hardware Revision: 1.0
Processor Speed: 447.28 MHz
DRAM: 1048576 MB
Flash: 128 MB

Firewall
Disable Firewall for True Static IP Subnet Only: OFF
Disable Gateway Smart Packet Detection: ON
Disable Ping on WAN Interface: OFF

Firewall Security Level: Minimum
LAN-to-WAN: Allow all
WAN-to-LAN: Block IDENT (port 113)

Local IP Network
IP Address (IPv4): 10.1.10.1
Subnet mask: 255.255.255.0
DHCPv4 Server: Enabled
DHCPv4 Lease Time: 7d:0h:0m
Link Local Gateway Address (IPv6): fe80::481d:70ff:fede:dcc8
Global Gateway Address (IPv6): 2603:3024:1705:3c00:481d:70ff:fede:dcc8
Delegated prefix: 2603:3024:1705:3c00::/56
DHCPv6 Lease Time: 7d:0h:0m
IPV6 DNS: 2001:558:feed::1

WAN Network
Internet:Active
Local time:2018-05-26 14:11:06
System Uptime: 4 days 16h: 56m: 42s
WAN IP Address (IPv4): 50.242.89.126
WAN Default Gateway Address (IPv4): 24.5.176.1
WAN IP Address (IPv6): 2001:558:6045:bf:31e4:2d63:9158:8238
WAN Default Gateway Address (IPv6): fe80::201:5cff:fe65:4c46
Delegated prefix (IPv6): 2603:3024:1705:3c00::/56
Primary DNS Server (IPv4): 75.75.75.75
Secondary DNS Server (IPv4):75.75.76.76
Primary DNS Server (IPv6):2001:558:feed::1
Secondary DNS Server (IPv6):2001:558:feed::2
WAN Link Local Address (IPv6): fe80::4a1d:70ff:fede:dcc7
DHCP Client (IPv4):Enabled
DHCP Client (IPv6): Enabled
DHCP Lease Expire Time (IPv4): 2d:10h:53m
DHCP Lease Expire Time (IPv6): 2d:17h:59m

Managed Sites: Disabled
Managed Services: Disabled
Managed Devices: Disabled
Port Forwarding: Disabled
Port Triggering: Disabled
True Static IP Port Management: Disable all rules and allow all
   inbound traffic through
Remote Management: Disabled
DMZ: Disabled
NAT: Disable All
Static Routing: None
Dynamic DNS: Disabled
Device Discovery: Disabled
Post Closed as "Needs more focus" by Ron Maupin♦
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George Moromisato
George Moromisato
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Slow performance with Cisco Comcast Business router with static IP address

I have a server with a static IP address connected to a Comcast Business router (Cisco DPC3941B).

I also have a second machine directly connected to the same router. It gets assigned a NAT address 10.x.x.x.

When the second machine connects to the server (or vice versa) I get very slow performance. For example, if I do an RDP connection from the second machine to the server, the screen draw is unbearably slow. Similarly, an HTTP connection from the second machine to the server (via a browser) is noticeably slow.

However, when connecting to the server from an outside network, everything seems fine. No unusual delays or performance problems.

The exact same set up with a different router (a Motorola one) did not have this problem.

Is this a problem/limitation with this router? Why? Is it the translation over the NAT? Why is that so slow?

Or is it something about my set up? Could I have misconfigured something on the server or router?

Any suggestions for debugging/diagnosing?