Welcome to Vodafone Community
Would you be ok looking at this Vodafone troubleshooting help page @dunky50 and if necessary use the Option Not Listed to run a TraceRoute and report back your finding
Either customer services on 191 or Live Chat can access your account and resync your ss too or.one of the Team here can.
On a side note > "It may also be worth trying a different power supply with the SureSignal (Version 1 & 2 ), even if it still looks ok regarding lights etc as there have been some reports of replacement power supplies solving the issues as they can degrade. They are available on eBay for around £10.From member cineriv "But firstly, have a look around for a suitable unit with a 12 Volt output @ around 1.5Amp capacity that you could 'borrow' to prove the fault. Suitable units can be found on external hard drives, monitors, printers, routers etc.etc."
Current Phone > Samsung Note 9 _512Gb > Model: SM-N960 Hybrid-Duos.
Samsung One Ui / Pie.
Samsung Gear s3 Frontier Watch.