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ASA 5505 L2L VPN using 4G networks(setting MTU and TCP-MSS)

Hello all,

I was hoping to get some insight into some site to site configuration using 4G networks on the Cisco ASA. I have two sites with a 4G backup internet connection. I've been having issues getting this VPN tunnel to stay up. Thse are typical static tunnels using PSKs. These tunnel do establish, but they will not stay established for very long and sometimes get stuck in a MM_WAIT_MSG2 state.

I'm wondering if the solution lies in setting MTU and TCP-MSS on my 4G outside interface. The manufacure suggestions setting and MTU of 1350, which would then mean I would set TCP-MSS to 1248. Also, if I do change thse settings. Does this force me to make the same change to the tunnel endpoint even if it is not a 4G connection.

Any help would be appreciated, thank in advance!

Best regards,


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