How to identify the cause of the rx-too-long on MikroTik?

Good day
Have on hand the model 3011Ui(6.46.2), via the sfp port is accepted by client traffic(~100-150 Mbps l2, cell base station), leaking through the EoIP tunnel to another Mikrotik. After connecting, the client began to complain of increased loss(formerly the joint was at a different address), which is strange, given the more powerful hardware and a smaller number of hops to the output point in the diagnostic process noticed that the sfp port is fast growing the value of the parameter rx-too-long(about 1K/s), while on the interface and bridge exhibited 1700 L3 MTU and L2 MTU of 4096. Tried to put value more, but the counter never ceases to grow, the client traffic from your side also checked and they say I don't see anything. On of the forum no information on this problem is not found, in your opinion this is a bug or not? How to identify the cause?
April 7th 20 at 10:55
2 answers
April 7th 20 at 10:57
Apparently this is some new bug glands, stuck in the gap and put another Mikrotik(960pgs), this counter is not growing.
April 7th 20 at 10:59
rx-too-long (integer) Total count of received packets that were larger than the maximum packet size

You have come on the packet size
I read, but somehow doubtful. And L3 and L2 MTU has increased, not in any way affected. I will try the gap to stick the switch and look at its counters. - dasia commented on April 7th 20 at 11:02

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