Trouble pinging a static IP on a remote Mikrotik via VLAN?

Question

Computer networks

In the office, there is a crs125-24g-1s-in microtic, which is conditionally the main one, with a DHCP server raised, an Internet channel is connected to it and 15 branches are collected via VLAN L2. When a new branch appeared, the provider usually simply turned on a new point, and we installed the receiving Mikrotik, and everything worked. It was not possible to get our provider to the last shopping center and we took VLAN L2 from another provider, which threw cables both to the office and to the point. The following problems arose - when turned on in the morning, Mikrotik does not ping the servers in the office and does not receive the Internet. If you restart it, everything works as it should. Thus, the equipment is first started when the electricity is turned on in the sales department, and then a manual reset is required to make everything work. With no provider equipment in the department, there is only a cable.
After that, Mikrotik receives an IP address from the office network and all equipment works, except for one counter, which has a static IP in the office subnet. He refuses to respond from the office, and from the sales department responds perfectly. At the same time, several times I caught him on the fact that he spontaneously started to ping and then spontaneously fell off, although he constantly kicks from the sales department, that is, this is not a cable problem. Where to dig in this situation - I do not know.

Answer 1

Making extended L2 domains is a so-so idea. In the case of your counter pinging and not pinging, you can assume that the problem is duplicate MAC addresses on the network, or someone (or something) is spoofing poppies.
Draw a network diagram. And then nothing is clear: "office", "point", "shopping center", "trading department" - "who are all these people ?!"
I will also add that providers are often not present with their network at the connected objects, so the "tunnel within a tunnel over a tunnel" solution can easily be used, although you will see "as if one L2 domain". But as you understand, such nesting of technologies cannot but create problems under certain conditions. Maybe you should think about moving to L3 and networking based on your VPN over L3,

Answer 2

it is quite possible that the equipment in the shopping center initializes the port longer than the mikrotik is loaded (for example, portfast is disabled for cisco + port type auto-negotiation). as a crutch, you can ask the provider for a static ip and register it yourself (without relying on dhcp) or add a restart port script to Mikrotik 5 minutes after the start.