u mean u hv lag on hypptv with vip10 now?
that shudnt be, mine all smooth, everyday, everytime.
speed problem? that's their job to fix it!
the usual culprit is either the modem or the router, so do check that..

all channels or always the same ones?

This is very weird tho. IPTV on UniFi does not use internet bandwidth, it has it's own 20Mbps VLAN. So when you're signing up for VIP5, you're actually getting VIP5 PLUS a secondary 20mbps line for IPTV.
+1. There is either something wrong with the IPTV box, something wrong with the modem or something wrong with the cabling.

On the topic of the IPTV box, which type did you receive? I have this theory- If it's the newer Huawei Android one, maybe he activated it in Streamyx mode instead of UniFi mode. Streamyx does not have VLAN so the IPTV simply leached off the internet connection, but UniFi does have VLAN dedicated to IPTV and the IPTV should use it.

i read back yr previous posts...

so, u were on vip5, upgraded to vip10 but using same equipment, no change right?
the hypptv stb did not work right from day1 with vip5, same now?

the stb u hv is the old type, but it works - i hv the same.
orange modem... if old equipment, orange is the color of the router.
the modem is white for old, silver for new replacement.
are the connections correct? shud be:
.. incoming fiber->modem
.. modem ->router; modem->phone
.. router port4->hypptv stb
.. router ports 1, 2, 3 ->ethernet

if connections all good and firm, i suspect the problem is coming from
1. modem-router network cable no good or
2. port4 of router malfunction
3. router->tv hdmi cable faulty

yes, that is the modem or btu.
how old is it?
mine was the same, lasted 3 yrs.
then, it started to act weird... phone could call out but can't receive, sometimes dead.
lights blinking goes beserk at times, but could use still.
i did not suspect the problem until it died one day, no light at all.
reported to unifi, r placed foc with new silver one, new network cable, all ok.
unifi guy said 3 yrs is extraordinary, most last 2 only.
if u dun hv similar symptoms, then it shud be still working fine.