@Freddo If I understand you correctly, you want to use an ER605 in front for WAN failover, isent it easyer with WAN failover on Cisco ASA,

@11MeG Gateway is blocked, try from the internet and not from LAN,

I have only tested site to site some VPN errors in this version., SHA2 don't works, also get errors when I try to change to SHA1, downgraded to 1.3.0 no problem.

@mihah OK, then I don't know, when I've had a problem with SIP I've either disabled or enabled SIP ALG, I don't know if it works on tp-link, I've only done this on other brands.

@mihah have you tried to disable SIP ALG?

@lflorack I can confirm that I have the same in the log on two different sites with ER605v1, it appeared on both sites when I upgraded to the latest firmware. I only have two sites with ER605v1 so...