P2P link with 4 VLAN - Huge number of errors on Ethernet Int

Dear all,

we have bought 2 RouterBoard RB711-5HnD - RouterOS 5.4 - Licence Level 4

We want to establish a Wireless Point-to-Point link between two Switch (HP 2520-24G-PoE). This link must transport 4 VLAN (ID: 1,2,3,100)

We have follow this guide: http://wiki.mikrotik.com/wiki/802.1q_Trunk_extension_over_Wireless_P2P_Link.
In this guide is explained how to create a backup link via WIFI.
In my case, I need a primary link via WIFI (so I don’t need any STP functionalities)

Following the guide I’m able to implement the WIFI link and I’m able to ping from side A all the IPs of side B and vice-versa (I have tested ping on all 4 vlans)
I’m not able to reach, from side B the web services of side A (but I’m able to ping, from site B, the address of web server on side A!!!).

I’m not able to understand where’s the problem.
I see a lot of errors on Switch port used by AP.

Switch side A
Errors (Since boot or last clear) :
FCS Rx : 3 Drops Rx : 0
Alignment Rx : 1 Collisions Tx : 22
Runts Rx : 0 Late Colln Tx : 0
Giants Rx : 0 Excessive Colln : 0
Total Rx Errors : 13 Deferred Tx : 114

Switch side B
FCS Rx : 20 Drops Rx : 0
Alignment Rx : 0 Collisions Tx : 520
Runts Rx : 0 Late Colln Tx : 1
Giants Rx : 0 Excessive Colln : 0
Total Rx Errors : 192 Deferred Tx : 123


Please tell me your opinions

Regards
Marco