How to downgrade to 5.11 from 5.15??? Urgent help

I upgraded yesterday two of my routerboards and one PC to 5.15 and from that time I get disconnected my PPPoE client and without restart of routers they can not connect. I had no problems till not. I tried to downgrade as it was 5.11 but it does not work I get message you have new packages installed? I need urgent help?

in files uopload the 5.11 routeros
then goto system package and press [downgrade]
restart and you have it

Downgrade will not fix your problems, just create some more. Better email support and solve the issue.

Your’e right but something must be wrong with this version as I told I had even one problem till now? So as a fast fix I will try to downgrade to see if it will work like before. Anyway thanks for your suggestions. And I am busy till the weekend and in order not to let my users without service I will try this. I just tried by putting packets to files and restart but it sais than you have newer version something like that. I will tried from sugestions by checkin downgrade for the packets to se if it will work.

pay attention: before downgrade give an /export file=old
in case the downgrade reset you something

Thanks for your help. I downgraded to 5.11 and I am back. I before downgrade checked and see that it said e.g. 10 connected clients but no trafic Rx/Tx are zero(0) no trafic at all. I downgrade only RB433 that was making problems to me, that it had 2 WLAN cards one in 2.4 and one 5 (disabled) not in use. Other 2 RB and one PC I have no problems they run 5.15.

Thanks again for your help.

Below some info.
All interfaces are in the same bridge LAN.
Wireless (Atheros AR5413) running in 2.4
Wireless (Atheros AR5213) running in 5 - disabled not in use.