Hub 3, SNMP port forwarding not working

[David-J-Taylor]

Hello,

Dual NAT/SNMP issue - I am trying to give external access to three devices on my LAN to someone in Switzerland.  For other purposes, port 9742 works, but I can't get other posts to work.  My setup is HUB 3, Netgear router, Wi-Fi access point.

Hub 3 in router mode, no Wi-Fi
DHCP start 192.168.200.10
reserved IP 192.168.200.5 for Netgear router
Port forwarding: WAN port 9742/UDP => LAN 192.168.200.5, port 9742
Port forwarding: WAN port 9745/UDP => LAN 192.168.200.5, port 9745
Port forwarding: WAN port 9746/UDP => LAN 192.168.200.5, port 9746
Port forwarding: WAN port 9747/UDP => LAN 192.168.200.5, port 9747
=>
Netgear router, no Wi-Fi, runs DD-WRT
WAN IP 192.168.200.5
Port forwarding: WAN port 9742/UDP => LAN 192.168.1.20, port 9742
Port forwarding: WAN port 9745/UDP => LAN 192.168.1.30, port 161
Port forwarding: WAN port 9746/UDP => LAN 192.168.1.31, port 161
Port forwarding: WAN port 9747/UDP => LAN 192.168.1.32, port 161
=>
Wi-Fi access point

So given that port 9742 works, I believe I have things basically correct, and that somewhere along the route SNMP is getting blocked.  Perhaps I've missed an odd setting somewhere?  What might be the best approach to diagnosing this problem?  It could be in the DD-WRT configuration, or the Hub 3.  Yes, Modem Mode might be the obvious choice, but that halves the speed from the Hub 3!

Perhaps this rings a bell with someone?

Thanks,
David

[DJ_Shadow1966]

Hello David

Exposing SNMP to the internet certainly isn't something I would recommend, if you require to use SNMP then personally I would recommend setting up a VPN, SNMP is so easy to hack and really is only meant to be used on local networks.
Regards Mike

[David-J-Taylor]

Yes, in general, I agree.  However, the devices I'm using are highly specialised satellite receivers with no direct connection to the rest of the network.  They are not "PCs" in any sense., and don't run an operating system as such.  In practice it would only be run for short periods.

[Tudor]

"Yes, Modem Mode might be the obvious choice, but that halves the speed from the Hub 3!"

Why? I have only ever run all my VM hubs in modem mode and never got half speed. Something is wrong with your setup.

[David-J-Taylor]

It seems to be well documented here.  In my case the 350 Mbps service showed as around 200 Mbps in modem mode, but well over 350 Mbps in router mode.  I don't know why.  200 Mbps service was just OK.

[legacy1]

DD-WRT can limit your speed see what speed you get in modem mode without a router

[David-J-Taylor]

I am now seeing well over 350 Mbps running in router mode, with DD-WRT on the Netgear router, and an Wi-Fi access point beyond.  As this is a working installation I cannot use it for test purposes, much as I would like to try your idea.

[legacy1]

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@David-J-Taylor wrote:

As this is a working installation I cannot use it for test purposes.

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so whats wrong why are you here?

[David-J-Taylor]

As I wrote to start with: What might be the best approach to diagnosing this problem?  How to discover where the blockage is?  Having SNMP would be helpful, but is not critical.

[David-J-Taylor]

Thanks, Mike, but just to point out that it would not be on port 161, of course.