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MTU Size issue?

KGrev
Level 4
Level 4

Hi, I'm trying to resolve an issue im having with a vpn connection to a mobile LTE Router (IR 809G)

Normally the connection and throughput is fine, however i'm being required at add an encryption device to one router to form a link to another encryption device inside out network.

  • Throughput of lte routers normally = many megs
  • throughput through encryption device through lte router = 56k hard lock
  • throughput of encryption devices connected to switch = 100meg

I'm wondering if im having an mtu issue pushing a tunnel through a vpn on the lte router.

When I send a ping with df-bit from LTE router (not through encryptor device) it begins to fragment at 1439.

 

Router vpn terminates to an ASA also.

 

I've dropped the mtu on the encryption devices well below this but have not noticed a change.

 

Any ideas?

16 Replies 16

(I may be reposting as my post keeps going away)

 

Attached LTE Router Config.

More information,

Here is a picture from the laptop sending pings till the MTU is too high. It drops of at 1397 while connected to the encryption devices.

20220419_122726.jpg