Why is the browser so interesting?

Question

System administration

Good day everyone!
Friends, save! I've been struggling with this problem for 3 days now. There are no more ideas :(
The problem is this. The beginning. There was a zuksel router in the organization. I change it to Mikrotik. And some clients start having problems: I open a browser (any), I type a site in a search engine, for example, drive2, and I get ERR_TIMED_OUT. Search engines work all , some sites open without problems, Windows 7.10. Mikrotik plowed all over, turned off the firewall , wire \ wireless - nothing changes. (I've been friends with Mikrotik for a long time)
.
, the antivirus demolished ...
I will be very grateful to you!
PS admin since 2004

Answer 1

https://forum.mikrotik.com/viewtopic.php?t=29114

Answer 2

ICMP by chance don't drop it on purpose?
Kofig in the studio!