MikroTik

What is wrong here?  I can ping upgrade.mikrotik.com IP address, also i don't have any firewall blocking anything. I have same identical device in VRRP (HA) pair which has no issue. 

[admin@fw5] > /system package update check-for-updates
          channel: bugfix
  current-version: 6.34.2
           status: ERROR: connection timed out

[admin@fw5] > ping upgrade.mikrotik.com
  SEQ HOST                                     SIZE TTL TIME  STATUS
    0 54.230.141.151                             56  46 75ms
    1 54.230.141.151                             56  46 75ms
    2 54.230.141.151                             56  46 75ms
    3 54.230.141.151                             56  46 75ms
    sent=4 received=4 packet-loss=0% min-rtt=75ms avg-rtt=75ms max-rtt=75ms

Do you have a 1500 byte MTU all the way between your device and the update server?
(i.e. no PPPoE or VPN along the path)

If not, make sure you have a rule to clamp the MSS to PMTU.  The update server does not process ICMP "packet too large" replies correctly.

In my case that was firewall rules. Was fixed by disabling some of them.

I had this same issue with disabling firewall rules in order to get the upgrade to succeed. I posted my data on another thread here in the forums: viewtopic.php?f=2&t=111054&p=675438#p675438

Hi all!

One more reason for this problem - ROS upgrade fail with these symptoms:

finding out latest version...
ERROR: connection timed out

Special 'option' package installed. I don't know how normal user can do that, but it was done to my device by MikroTik support team. They installed it and left it forever. And no one informed me that it's potentially dangerous and can affect to the normal device functionality. BTW, it remains even when ROS have been updated manually or/and device restarted. So, I lived with this package for 1 year!!!

Here is how this package looks like:

How to solve the issue?

Press Uninstall, it will change appearance to grayed-out and change status to Scheduled. Then, reboot the device.

And you are done! Now you can upgrade ROS by pressing Check for Updates.