RB450G some (one) sites not working

Hello!

I’ve got problem with RB450G, here is the setup:

  • WAN IP address obtained by DHCP from ISP
  • IP obtained from ISP is private but ISP maps 1:1 routable IP to my private one
  • there is a EoIP+PPTP connection to another site (the same ISP - no public address mapped) - bridged with lan

The problem is that I cannot conenct with one (only one confirmed, maybe there is more) host on the Internet. Ping gets timeout, traceroute stops at the last hop. The host was responding until one morning - router’s configuration was not touched at this time.

The problematic hosts responds on the second site, and right now I’ve created a static route on the first site that routes the traffic to the problematic host thru the second site - and in this setup the host is responding on the first site as well.

I tried to increase MTU - no luck. ISP came to the first site and connected directly to line with the same IP address and said that everything is fine - host is responding.

What could be wrong? RouterOS is v5.16.

I would first make sure the problem is really related to your mikrotik router. don’t just take your isp word for it. test it yourself. plug-in the cable directly to a pc and see whether you can ping the host in question.