TOS 3.10
openvpn-openssl 2.4.4-1
The openvpn package txqueuelen is default set to 100 and as a result a high txdrop ratio (in the range of 1-2%) in the tunX iface was observed, particularly incurring when downloading large files over the tunX. This setting is curing the issue.
/etc/config/openvpn
option txqueuelen '1000'