Problem with PPPoE connections after upgrade to 6.42.1

RouterOS General
1

Hello.
On last friday our main router (CCR1036-8G-2S+) was upgraded from 6.37 to lastest stable routeros. From this time some client has problem with some connections - netflix, skype for bussines, online radios, speedtest.net - just can’t connect to specified services. But for example they can connect for example to speedtest.pl - download it’s ok but upload it’s about 0,2 mbps. Problem occurs only on some devices - linux mint 17 pppoe client, Dlink dir 605l router, some asus devices.

I can see client connections on router on all interfaces, connection occurs in ip->firewall->connections with correct state, router doesn’t log nothing strange, but for some reasons clients can’t connect to random pages.


Any ideas?

2

I found the problem - if on clients devices was set MTU > /interface pppoe-server server max-mtu, problem happens. But I don’t know why this problem occurs - packets bigger than max-mtu should be splitted, because mrru it’s set to the same value as max-mru, right? Mikrotik staff?

3

I believe problem in switching. Because of TCP MSS negotiation. After this frames with vlan tag of 1512 bytes, for example, can’t get through switch ports with MTU 1500. But with PPPoE MTU 1480 it can.

4

We did not change anything in our switches, only upgrade routeros.
As I wrote, setting MTU lower that 1480 helps, but another strange things happens. Packets count on interface pppoe grows to very high values. I collect data from:

/interface print stats-detail

And output looks like:

410 DR  name="<pppoe-kmedrala1>" last-link-up-time=may/14/2018 16:50:24 
       link-downs=0 rx-byte=196 979 539 tx-byte=10 237 853 430 
       rx-packet=3 706 128 tx-packet=7 065 682 rx-drop=0 tx-drop=0 
       tx-queue-drop=0 rx-error=0 tx-error=0 fp-rx-byte=0 fp-tx-byte=0 
       fp-rx-packet=0 fp-tx-packet=0

Pps graphs look like this:
pps_kmedrala1-week.png
Routerboard was upgraded on 12 may. Traffic on interface pppoe-kmedrala1 it’s very low.

Mikrotik team, can you look at this post?

5

Mikrotik team? It’s look like some bug.