OpenWrt 18.06.1 as guest under XenServer 7.2 bridge speed

XenServer 7.2 (all updates installed)
Virtualized OpenWRT 18.06.1 (stable from site x86_64)

Wireless Adapter QCA9880 (HVM PCI passthrough)
Virtualized Network Adapter of Xen

All configuration is simply done, and WiFi works under HVM OpenWRT, have add virtual network interface (bridge with LAN interface of Xenserver), then add it in Wireless configuration in web interface to bridge it, and do some speedtest over WiFi connection (from other VM -> Virtual Ethernet bridget with WiFi -> WiFi client) - download is great (maximum as possible), but upload (from WiFi -> WiFi bridget with Virtual Ethernet -> other VM) is terrible - it's all time about 0.1-0.2 mbit (and TX packets is dropping on Ethernet interface)!

I have install samba on guest OpenWRT to test download/upload speeds - all is great, speeds about maximum of WiFi speed. So - WiFi works normal.
Than i try to test download/upload from OpenWRT to Xen (over Virtual Ethernet) - and all is great, speeds about maximum about OpenWRT storage speed!

I have try routed network (NAT) and speeds is better, but not good - download is about maximum of WiFi, upload about 10-20 mbit and very high unusual CPU usage.

Then i have installed in same environment CentOS 7.5 with hostapd (same bridget Virtual Ethernet with PCI Passthrought WiFi) and it works good without any issues of speeds and CPU usage is not noticeable at all.

Then i try to compile kernel with Xen guest support in kernel_menuconfig, but nothing changed.

So, it's looks like problems in OpenWRT bridge with Wireless and Xen virtual Ethernet (before, i have successfully get it to work with same hardware in Hyper-V without any problems). Maybe i need to configure OpenWRT bridge to work properly with Xen virtual Ethernet, but i did not found any information on the web about it.

Are you using the Paravirtualized Adapter, or the AMD/Intel emulated ones?

Have used Paravirtualized Adapter.
I have try to using internal (Single-Server Private Network) and External Network (based on NIC) each of them works identical with low speed OpenWrt bridge bug.
But when i make PCI Passthrought of Physical Ethernet NIC - it works without issues.