'Cause and effect'  - No streaming or internet based TV service will work without stable internet. 

If your internet has any issues, this will affect streaming TV viewing. 

The most commonly used check is a speed test. This can be misleading.

A speed test is a 30-60 second or so ‘snapshot’ of the internet taken at the time. It is not a measure of continual speed or ongoing stability, which are essential for any streaming TV services. If the internet speed, drops - even briefly. below the required amount your TV service requires - then you will see issues.

Each internet connected device is seen individually (as a connection)  by the internet provider.  Each connection can be controlled/throttled by internet service provider, so a speed test done on a computer, will not provide information on other devices, nor gives help in reviewing the stability of the internet.

Internet issues can be down due to a number of reasons, including:  Localised technical faults, overloading - too many people online for the ISP to deal with to maintain stability of service.

Additionally internet providers can target a single device connection - so if low on resources, it is possible to throttle (slow down) a specific connection.  Internet providers buy in bandwidth, based on the amount of users 'they believe' will be online at any given time, if they exceed this problems begin and they may take steps to balance their network. 

None of this is visible to the internet user.

Pixellation, picture freezing or stuttering, temporary pausing, blank or black screen. Picture disappearing, then re-appears or screen error message - ‘page loading errors’. 'Missing file errors'.  Files taking longer than usual to load.

Initially reboot the router, power mains off. Also power off (power out, not standby) IPTV set-top box. Power up the router first, 3-5 minutes before the TV box, as this allows time for the router to establish the internet connection. If you have a hardwire / ethernet connection from your TV box, directly to the router (IE not using WiFi), then you can also try to change the port in the router the box is connected to, there are usually a few spare ports available.

If you are having problems with a specific channel - for example 'BBC1 freezes or buffers' - then try to change channel for a couple of seconds - go to (example) BBC2, then go back to the original channel. Sometimes 're-establishing' the connection stream can help. If the internet drops, it can freeze the channel streams, so by changing channel and back again, this can cure if there was a brief internet issue at the time. If still an issue with one channel and others OK - then it is recommended you drop your TV provider a quick email with the channel name/number and ask them to check. Standard definition uses less data than HD - so if having issues at the time, then you can try content not marked HD (Standard Definition).

Connection or portal throttling - Targeting the specific portal the IPTV or streaming service is using. TV services / Video can use 20-30 times the amount of data someone browsing the internet does. 

If your internet service provider struggles with resources during peak periods, they can throttle the specific portal of your TV or each individual streaming device. To summarise, you can have 100Mbs fibre optic connection, with that showing that on a speed test when testing on your computer, yet your TV box or other device using for streaming,  could actually be only be seeing 1Mbps! This makes a nonsense of the validity of a speed test reading as the service provider can alter the connection speed to each individual device. This then confuses end users who then run a speed test on their (example) laptop, which gives a completely different reading altogether. Summary, speed tests can be quite deceptive. 

ISP’s are aware that people cannot easily check or measure this, often an hour or two later, things get better - usually when less people online! Or the following morning.

Unfortunately software to test for this type of throttling or traffic shaping, which is deliberately controlling the flow of data for your specific service, is commercial type software and not something easy to use or readily available like a generic speed test. Why are there no good truthful generally available software available to test this type of ongoing stability - to really see what ISP's are doing? You can probably guess the answer - they simply don't want you to know.

What can you do to check if issue is with your ISP?  If for example you have friend or family nearby, give them your box or service for the night and see if it behaves in the same manner on their internet - must be a different internet service provider.

Self test your internet connection - To establish if issue is with the internet service or the TV service. 

Either use a different internet providers connection (friends/family) or, if you have a 'mobile hotspot' option on your smartphone - you can share your internet connection, locally for other WiFi equipment. If you have an IPTV box capable of WiFi, create mobile hotspot connection, then connect the box to the new mobile connection - just as a quick test it won't use too much of your mobile data. This is a good option if you do not have another landline/fibre option of a different internet provider to check. Check the same channels which you had problems with, on your regular landline internet - if they work ok on your mobile connection - then you know the issue is with the internet provider. If the problem channel is still same on different internet connection - then you know it is a TV service issue & not an internet issue tripping up the TV.

WiFI - Most equipment is now supplied with Wi-Fi option. Whilst convenient, depending on the location of your IPTV device in proximity to the router, this will affect the signal. The further away you are & with walls in between, this can reduce speed & other electronic devices such as home portable phones, can interrupt Wi-Fi. Make sure your Wi-Fi signal is good if using and if you start off with slow speeds, then a cable or MESH type system *signal booster, may prove a faster and more stable option.

Wi-Fi is convenient, due to the obvious lack of cables. However, performance wise, cable always offers the fastest and most stable option with the least losses in both speed and stability.

VPN / Proxy DNS & Privacy - If requiring privacy from your internet service provider, it is possible by use of a VPN or DNS Proxy service. This type of service can be added into some existing IPTV set top boxes, though not all hardware is designed to add in a VPN service, so will need to check the model of your equipment to see if available.

You may be able to add in a DNS Proxy to your existing equipment or router - example  Smart DNS proxy. You can also add privacy to all connections within a property by use of a VPN router. This connects to your existing router and then with the inbuilt VPN service gives you both privacy and location options if overseas and wanting to access content in different countries which is usually geographically restricted. Example of VPN router service.

If you have for example 'Android' equipment a smart TV, it is possible to add in a VPN app & service within your equipment - not possible with MAG type hardware. An example of a popular VPN services (not affiliated) Express, Shark or Nord VPN.