For the records, I'm getting the same result with RB800 upgraded to 5.5.
[engenharia@MikroTik] > /log print
(...)
21:12:09 pppoe,info PPPoE connection established from 00:1E:4F:FD:9B:A6
21:12:09 pppoe,ppp,info <pppoe-0>: waiting for call...
21:12:09 pppoe,ppp,debug <0009>: LCP lowerup
21:12:09 pppoe,ppp,debug <0009>: LCP open
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP ConfReq id=0x0
21:12:09 pppoe,ppp,debug,packet <mru 1480>
21:12:09 pppoe,ppp,debug,packet <magic 0x4be0541b>
21:12:09 pppoe,ppp,debug,packet <pcomp>
21:12:09 pppoe,ppp,debug,packet <accomp>
21:12:09 pppoe,ppp,debug,packet <callback 0x06>
21:12:09 pppoe,ppp,debug,packet <0009>: sent LCP ConfReq id=0x1
21:12:09 pppoe,ppp,debug,packet <mru 1480>
21:12:09 pppoe,ppp,debug,packet <magic 0x60bb2ee5>
21:12:09 pppoe,ppp,debug,packet <auth pap>
21:12:09 pppoe,ppp,debug,packet <0009>: sent LCP ConfRej id=0x0
21:12:09 pppoe,ppp,debug,packet <pcomp>
21:12:09 pppoe,ppp,debug,packet <accomp>
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP ConfAck id=0x1
21:12:09 pppoe,ppp,debug,packet <mru 1480>
21:12:09 pppoe,ppp,debug,packet <magic 0x60bb2ee5>
21:12:09 pppoe,ppp,debug,packet <auth pap>
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP ConfReq id=0x1
21:12:09 pppoe,ppp,debug,packet <mru 1480>
21:12:09 pppoe,ppp,debug,packet <magic 0x4be0541b>
21:12:09 pppoe,ppp,debug,packet <callback 0x06>
21:12:09 pppoe,ppp,debug,packet <0009>: sent LCP ConfAck id=0x1
21:12:09 pppoe,ppp,debug,packet <mru 1480>
21:12:09 pppoe,ppp,debug,packet <magic 0x4be0541b>
21:12:09 pppoe,ppp,debug,packet <callback 0x06>
21:12:09 pppoe,ppp,debug <0009>: LCP opened
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP Ident id=0x2
21:12:09 pppoe,ppp,debug,packet <magic 0x4be0541b>
21:12:09 pppoe,ppp,debug,packet MSRASV5.20
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP Ident id=0x3
21:12:09 pppoe,ppp,debug,packet <magic 0x4be0541b>
21:12:09 pppoe,ppp,debug,packet MSRAS-0-NITLAB
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP Ident id=0x4
21:12:09 pppoe,ppp,debug,packet <magic 0x4be0541b>
21:12:09 pppoe,ppp,debug,packet +j\BC-\AE\83MH\AE\E5\0E\83\B3\12\E6B
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd PAP AuthReq id=0x19
21:12:09 pppoe,ppp,debug,packet <user 5511000000>
21:12:09 pppoe,ppp,debug,packet <password 5511000000>
21:12:09 pppoe,ppp,debug,packet <0009>: sent PAP AuthAck id=0x0
21:12:09 pppoe,ppp,debug,packet Login ok
21:12:09 pppoe,ppp,debug,packet <0009>: sent CBCP CallbackReq id=0x0
21:12:09 pppoe,ppp,debug,packet 01 02
21:12:09 pppoe,ppp,info <pppoe-0>: authenticated
21:12:09 pppoe,ppp,debug <0009>: IPCP lowerup
21:12:09 pppoe,ppp,debug <0009>: IPCP open
21:12:09 pppoe,ppp,debug,packet <0009>: sent IPCP ConfReq id=0x1
21:12:09 pppoe,ppp,debug,packet <addr 200.202.114.153>
21:12:09 pppoe,ppp,debug <0009>: IPV6CP open
21:12:09 pppoe,ppp,debug <0009>: MPLSCP lowerup
21:12:09 pppoe,ppp,debug <0009>: MPLSCP open
21:12:09 pppoe,ppp,debug,packet <0009>: sent MPLSCP ConfReq id=0x1
21:12:09 pppoe,ppp,debug <0009>: BCP open
21:12:09 pppoe,ppp,debug <0009>: CCP lowerup
21:12:09 pppoe,ppp,debug <0009>: CCP open
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd CBCP CallbackResp id=0x0
21:12:09 pppoe,ppp,debug,packet 01 02
21:12:09 pppoe,ppp,debug,packet <0009>: sent CBCP CallbackAck id=0x1
21:12:09 pppoe,ppp,debug,packet 01 02
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP ProtRej id=0x5
21:12:09 pppoe,ppp,debug,packet 82 81 01 01 00 04
21:12:09 pppoe,ppp,debug,packet <0009>: rcvd LCP TermReq id=0x6
21:12:09 pppoe,ppp,debug,packet K\E0T\1B\00<\CDt\00\00\02\D0
21:12:09 pppoe,ppp,debug <0009>: LCP closed
21:12:09 pppoe,ppp,debug <0009>: CCP lowerdown
21:12:09 pppoe,ppp,debug <0009>: BCP lowerdown
21:12:09 pppoe,ppp,debug <0009>: BCP down event in starting state
21:12:09 pppoe,ppp,debug <0009>: IPCP lowerdown
21:12:09 pppoe,ppp,debug <0009>: IPV6CP lowerdown
21:12:09 pppoe,ppp,debug <0009>: IPV6CP down event in starting state
21:12:09 pppoe,ppp,debug <0009>: MPLSCP lowerdown
21:12:09 pppoe,ppp,debug,packet <0009>: sent LCP TermAck id=0x6
21:12:09 pppoe,ppp,debug <0009>: LCP lowerdown
21:12:09 pppoe,ppp,info <pppoe-0>: terminating...
21:12:09 pppoe,ppp,debug <0009>: LCP lowerdown
21:12:09 pppoe,ppp,debug <0009>: LCP down event in starting state
21:12:09 pppoe,ppp,info <pppoe-0>: disconnected
21:15:24 system,info,account user engenharia logged in from 200.202.114.16 via telnet
[engenharia@MikroTik] >
[engenharia@MikroTik] > /system resource print
uptime: 15m39s
version: 5.5
free-memory: 238912KiB
total-memory: 256320KiB
cpu: e500v2
cpu-count: 1
cpu-frequency: 799MHz
cpu-load: 0%
free-hdd-space: 482944KiB
total-hdd-space: 520192KiB
write-sect-since-reboot: 261
write-sect-total: 25310
bad-blocks: 0%
architecture-name: powerpc
board-name: RB800
platform: MikroTik
[engenharia@MikroTik] >